Because the rich white guys who own things in Hollywood don't want to see more POC--it's why they doggedly hold that everything needs to be marketed to the 18-35 yr old straight white male audience despite all evidence that says that there are other markets to mine--it's the world as they want to see it and that matters even more to them than making money--which is scary, because they love them their money. You won't see more older women of any color there, either.