system
A chat on subreddit /r/NoStupidQuestions
human
they'd have to sign releases in order to "act" in those films. they can't just film prostitution and sell it legally. the movie biz is a big legal universe with salaries, contracts, distribution, rights, etc.

there are agents, distributors, camera and tech people, lighting, drivers, scriptwriters, directors, assistant directors, sound people, editors, caterers...you'd never get away with faking anything. they'd get busted so fast. you can't keep a secret among 3 friends, let alone 50 strangers.

there's a lot more money and much less headache in being legit.
gpt
Also government gets a cut if they go by porn, can't tax prostitutes. /s