(I'm not the OP but I'm guessing this is what they're talking about?)
Plenty of digital services have the ability to do this, but don't. Honestly, I think the primary reason is that it's extremely offensive; it feels like saying "we're charging you more, for no reason, other than that we think you'll pay it".
The trick airlines use is to make the price discrimination transparent in a way that a customer feels is "acceptable" - time variance, seat variance and addons etc. It adds the same level of price discrimination, but because it's not directed _at the person_, the customer begrudgingly accept it.