From some googling, It seems like the median movie costs about $18M to make, while the average is about $70-100M and something like the avengers is around $200M. Oscar winners seem closer to median or average cost than avengers cost.

For shows, it seems to be in the $0.5-10M per hour range. I'll wave my hands lazily and call a season $5-100M.

If about half of US households spend $20/mo on these services, that's $16B per year. If half of that went to making movies and shows, it could make something like 500 median movies per year, 100ish average movies, or 40 avengers-caliber movies. For shows, it'd be 80-1600 seasons per year.

Apparently something around about 500movies and 500 shows come out each year.

I'm sure these numbers are way off, but the orders of magnitude are probably reasonable and suggest to me that $20ish/mo for everything ever is likely a little low, but not insane.