[bigstrat2003]

A significant difference here is that the airline fees are ostensibly optional. You could, in theory, fly Spirit with nothing except the clothes on your back and they wouldn't charge you extra. But with event ticket sales and the like, there is often no possible way to avoid the fees. That means there's a much stronger argument for requiring that the fees be rolled into the price.

[FateOfNations]

Or they do something silly where there is an "Online Convenience Fee" when you buy online, but if you try to buy it at the box office, there's a different "Box Office Ticketing Fee." The event promoter should pay the cost of their ticketing service provider(s) out of the money they make, not have the purchaser pay it separately.