Oh, that's simple. They are idiots that don't understand the product they sell.
Imagine that you are a best in the word graphic designer. And you have to sell your logo to someone, who literally don't see the difference between quality work and the logo that their nice did in ms paint.
In their mind those are the same picture, so why should they invest in you while you are 300x more expensive?
The don't see it, so their use data - that they also don't understand - to look for X factors and came up with idiotic conclusions like "star trek movies with older first captains perform better than movies with younger first capitan, so good script should have old one" or "movies with 3 joks per 5-minutes performe better than movies with one joke per 5 minutes"... or "jar-jar bings"...
When future comic book author of the masterpiece Bone finaly got his 5-minute meeting with publisher who was basicly a godfather-legend-who-is-who off paperstrips he heard "you should redraw all your comics so all speech-bubbles are thought-bubbles. Garfield uses thought-bubbles, and it's so successful".
It's the same reason why all all translations are shit now. People who decide are not literate enough to distinguish nuances of top-level translations from product if Google translate.
You're thinking additional 30k to make sure that a script is good is rounding error in the cost of the movie. They are thinking, typing one page should take like 10-minuts right? So with $15/h...."
Remember, for them LOTR and Hobbit are "just as good" sources for epic blockbuster trilogy.
They are literally quality-blind. Cust-cutting is all they bring to the table.
That kind of blew my mind.