7 classic TV shows you (mostly) can't stream

"Knots Landing," anyone?

(NEXSTAR) — There's never been a bigger assortment of new TV shows to watch at any given time as there are these days. What's more, there's never been more ways to re-visit old favorites or discover older programs you missed.

But that's not to say you can find everything on streaming. Some of yesteryear's biggest TV hits still can't be found easily with a simple scroll through Peacock or Disney+. Below, we rounded up seven and explain how you can find them.

A note on the definition of "streaming" for this story: While some shows below can be found available for purchase digitally, they aren't available to stream as part of subscription plans without additional cost or ads. A show that you can pull up on Netflix right now would be considered "streamable," while a show that you must purchase through a digital marketplace (Apple TV, Vudu, etc) can be streamed but not without extra cost or effort — that's where the "mostly" from the headline comes in.

"Mama's Family"

This iconic 1980s sitcom, a spinoff of the "The Carol Burnett Show," appears via reruns on several traditional TV channels and on free ad-supported platforms like Pluto TV, but so far has never been available to stream on-demand on platforms like Netflix or Peacock.

Starring comedian Vicki Lawrence as the titular Mama (real name Thelma Harper), the series premiered in 1983 and ran for two seasons before its cancellation by NBC in 1984. Despite this early axing, "Mama's Family" became popular in reruns and was revived two years later and would run more successfully until 1990.

Aside from catching it on one of the previously mentioned channels, "Mama's Family" can currently only be purchased digitally through Amazon, Vudu or Apple TV. DVDs of individual seasons and the entire series can also be purchased.

"Three's Company"

This sitcom with its ever-infectious theme song arrived on ABC back in March 1977 and ran for eight seasons and 172 episodes. Originally starring the late John Ritter and actors Suzanne Somers and Joyce DeWitt as roommates with Norman Fell and Audra Lindley as landlords Mr. and Mrs. Roper, the show would go through several cast changes before its end in 1984.

The series spawned two spinoffs, the one-season Ritter-starring "Three's a Crowd," and the two-season "The Ropers."

Currently, "Three's Company" can only be seen on Pluto TV. In case you're curious, both "Three's a Crowd" and "The Ropers" can occasionally be found on Pluto TV, in addition to Tubi and Spectrum.

"Magnum P.I."

This ultra-80s crime drama starred the mustached Tom Selleck as private investigator Thomas Magnum. Even if you've never seen the show, images of Magnum's Ferrari 308 GTS Quattrovalvole and the show's Hawaiian setting probably ring a nostalgic bell.

The original "Magnum P.I." (CBS launched a remake in 2018, which ran for five seasons) aired from December 1980 to May 1988, comprising eight seasons and 162 episodes. For several seasons, the show was among the most popular on TV and stars Selleck and John Hillerman both won Primetime Emmy and Golden Globe awards for their roles.

"Magnum P.I." can only be purchased digitally on Amazon, Vudu or Apple TV, among others.

"Gilligan's Island"

This delightfully campy 1960s sitcom only aired for three seasons and 98 episodes but its impact and regard continues to this day. The show would have three TV movie sequels and two animated shows based on it — in addition to a stage musical, a 2003 novel and a 2004 reality show that was totally nothing like "Survivor," called "The Real Gilligan's Island."

"Gilligan's Island" can only be found on Tubi, though the entire series is available to purchase digitally or physically.

"Knots Landing"

There's a ton of material here that's not streaming. "Knots Landing," a spinoff of fellow primetime soap opera "Dallas," ran for 14 seasons and 344 episodes. By the time of its ending, "Knots Landing" was one of the longest-running dramas in history — beginning in the 1970s and ending in 1993. The California coast-set drama even outlasted "Dallas."

Much of the cast would later reunite for a miniseries and a documentary special. Cast members Ted Shackelford (Gary Ewing) and Joan Van Ark (Valene Ewing) later reprised their roles in an episode of TNT's "Dallas" revival, which ran from 2012 to 2014.

As far as hard-to-watch, this one takes the cake. "Knots Landing" is not currently available to stream or purchase digitally. What's more — only the series' first two seasons were ever released on DVD.

"Thirtysomething"

This show's absence from streaming — and pop culture in general — doesn't necessarily reflect its impact. During its four-season-eighty-five-episode run, this Philadelphia-set drama about younger adults and their fledgling families was nominated for a whopping 41 Emmy Awards (winning 13) and two Golden Globe Awards (winning two).

The show is also credited with helping popularize the phrase "Thirtysomething," was added to the Oxford English Dictionary in 1993. Among it other achievements is inclusion in several TV Guide "greatest of all-time" lists, in addition to numerous critical accolades during its run.

A sequel series called "Thirtysomething(else)" was also greenlit by ABC in 2019, with many of the show's original cast tapped to reprise their roles. ABC ultimately halted the project, however.

"Thirtysomething" is not available to purchase digitally but can be found on DVD.

"Homicide: Life on the Street"

This NBC police drama ran from 1993 to 1999, across seven seasons and a total of 122 episodes — plus a 2000 TV movie. During its run, the series received numerous accolades (including four Emmy Awards) and was critically acclaimed, even if it was never a ratings darling.

Though the show followed the work of detectives in Baltimore, the show crossed over three times with the much more popular New York-based "Law & Order," of which "Homicide" is often considered (even among creators), a sister show. The character of Det. John Munch (played by late actor Richard Belzer) even joined the cast of "Law & Order: Special Victims Unit" for 15 seasons once "Homicide" wrapped.

Despite the wide popularity of procedurals on streaming ("Law & Order," "Criminal Minds"), NBC has so far not brought "Homicide: Life on the Street" to streaming. Individual seasons and an entire series box set can be purchased, however.

What prevents a show from being streamable?

Without studios needing to shell out for physical packaging, you'd think placing older shows on streaming would be a no-brainer. But it's not that simple.

Increasingly, as USA Today explains, studios and streamers are only interested in shows that will garner new subscribers or create more ad revenue. If the costs to put a show on streaming aren't vastly counteracted by the new revenue it creates, companies will largely see it as not worth the effort or investment.

One of the biggest factors keeping some shows from streaming capabilities is music rights.

Back in 2016, Dave McIntosh, senior VP of business affairs and digital distribution for Shout! Factory, told Vulture that tracking down rights holders for music in a show can take years and can seriously costly, with some small portions of songs carrying a $15,000 or higher fee to bring them to DVD or digital streaming.

Music rights have left many TV shows in limbo, including the beloved MTV series "Daria," which was kept from DVD and streaming for years as each episode of the series could potentially contain dozens of high-dollar songs packed in by the music channel.

Though "Daria," a spinoff of MTV's "Beavis and Butt-head," eventually made its way to both DVD and streaming, most of the original music is gone — replaced with generic (royalty free) background music. Some fans of the show have even created archived Daria playlists to keep track of what was taken out, while some others took to Change.org to create petitions to re-release "Daria" with the original music.