A lot of the old shows have complicated rights issues. Streaming wasn't even dreamed of when the contracts were written, so there is often no language that covers it. Good business affairs people would have negotiated deals that are something like "all territories, all methods of distribution" but often they would be limited to "pay television", "broadcast" or "network". Additionally, production companies will often negotiate deals that have a limited term and will revert back to the producer. Traditionally, big production companies would employ "deficit financing" for their shows. They would sell limited rights to the show for an amount less than it cost to produce. That is - if a show cost $10m to produce they would license it to a network for say $8m for the "first-run" rights to broadcast the show, giving them a period of time to premiere and show current re-broadcasts of the show. After that term is done, the rights go back to the production company and they can re-sell the show for re-runs, syndication, or whatever and could potentially make much more money for the $2m they had to pay out of pocket. This still exists for the shrinking linear TV market, but now deals directly for streaming platforms are almost always 100% and they are straight buyouts of the production.