I don't "subscribe" to movies. I see/rent movies "a la carte" with no regard for which studio made it. Movies also have enormous costs and risk, which are both spread across titles and business partners.
In fact, most major media types can be purchased on a per-title basis (movies, books, music). TV shows are almost there too, with many titles on iTunes being delayed by just a few days or even one day.
So I don't think it is somehow impossible to do "because it's TV". I find it difficult to believe that with so much potential profit on the table that studios would be unable to risk investment.
What I have seen over and over again in multiple industries, is that the real reason behind consumer inconvenience is the desire to retain complete control.