Well, if you think of it, they're losing nothing except bandwidth. There's no middleman, so the money goes straight to them right for their hard work.
When people like Kanye grab $billions in album sales, he only got a fraction of it. If he got what his fans thought he deserved, he'd probably still be just as rich, since the only people who buy CD's like that have enough disposable income to make bad purchases like that. I'm not saying his loyal fans are wasting money, but I'm talking about the majority of fans that will buy anything they see shiny on a billboard. If the billboard said "Donate $20 through Paypal", they would probably do it, but find it a burden to have to learn how to use Paypal.