They already do charge different prices for the same seat, based on their assessment of the type of passenger you are.

You've picked an "evil" example, but what price discrimination really tends to look like is charging richer people more.

Prices are generally lowered for poor people because they'd rather have your $300 than have an empty seat. If you don't have $800, no amount of desperation will make you pay it - you'll just miss the funeral.

The counter example are “dollar stores”, that offer lower per-package pricing at much higher per-unit prices.