To be accurate, I should have restricted the statement to non-government-funded radio endeavors.

I have no idea if NPR could fund itself in real life with advertising or not, since it isn't really allowed to do so, and anyway, they like things just the way they are. They do have a large and loyal listenership, but I wonder how many of them would tolerate tofu ads on their stations.

A liberal blogger comments on Air America and advertising here.

Air America is bragging today about having grown to 48 stations. When Rush Limbaugh hit the ground nationally in 1988, he was already on over 50 stations. But I guess time will tell.