Off the top of my head: Libraries already exist, and the regulatory regime to oversee subscription services doesn't.
Meaning, no one has to do all the stuff required to bring a new government agency into being (including raising taxes or borrowing money), there are no new regulations to comply with (which would cost the streaming services more, which would cost you more), you don't have an new, unnecessary agency brought into being which will literally never go away and increase the size of permanent government we all have to pay for and live with, you haven't expanded the scope of government intrusion in our lives, etc.
Meaning, no one has to do all the stuff required to bring a new government agency into being (including raising taxes or borrowing money), there are no new regulations to comply with (which would cost the streaming services more, which would cost you more), you don't have an new, unnecessary agency brought into being which will literally never go away and increase the size of permanent government we all have to pay for and live with, you haven't expanded the scope of government intrusion in our lives, etc.