Keep in mind that it's not just because of the studios: it's also because of the various TV networks that the studios have signed exclusive re-broadcast deals

Keep in mind that it's not just because of the studios: it's also because of the various TV networks that the studios have signed exclusive re-broadcast deals with. That's why Netflix sublicensed the Starz's rebroadcast rights, and why those movies rotate in and out of being available to play on demand (since the rebroadcast rights are all windowed to specific periods of time, with different broadcasters getting the rights at different points in time). So it's all a very complicated problem. Movies that already have the rebroadcast rights sold off would be tough without the sort of cross-licensing Netflix does with Starz; the studios don't really have further control until those deals expire, since they're legally-binding, exclusive contracts. Rentals don't conflict with those exclusive rights, which is why the studios can license Amazon or iTunes to offer the movies for a fee, but can't license Netflix to stream them. What they could do is to stop doing those sorts of exclusive deals, but those deals bring in a fair amount of money, so someone like Netflix would need to pony up enough cash on their end to make up for the loss of revenue that would come with either the total loss of those broadcast deals or with the loss of exclusivity on those broadcast deals. But I'm sure that even renegotiating non-exclusive contracts to use in the future deals with existing broadcasters would take a pretty long time once they've decided to do it; those sorts of legal maneuverings take a long time. So certainly the studios could start trying to do something about it, but it's not a simple problem that they could just change their minds about and make go away instantly.