The difference is that in cable TV you are beholden to their schedule. You might subscribe to a channel that has exactly what you want and still be unable to watch it because you are not free at that time.
If stream had everything in one single service, who cares that it also has stuff that you don't have any interest in? You could spend every moment watching just the thngs that you want to, there was no downside to having things you don't care about. It's such an archaic mindset to assume the price is bound to potential availability on an on-demand service.
Netflix used to be priced affordably and have nearly everything. We are seeing now with services being split and prices rising that it doesn't cost more because it has more shows, just on the contrary. It costs more because they think they can charge more and get us to subscribe to multiple services that offer less.