I have AT&T and to be honest I would rather listen to NPR on the radio rather than streaming/using my data. My data rolls over. So wasting it on something I could get for free anyway doesn't seem fair.
I mostly listen at home so data usage is not an issue. Even on mobile I hardly use the data I get with my plan (5.5GB month and I barely use 500MB) so it doesn't really matter what I use it for.
There's a certain retardedness to streaming a live radio station over the internet when you have an actual radio available and are in the broadcast area of the station.