Belaboring the obvious:
Though there is little to be offended by in most of NPR's programming, public radio and television cater almost exclusively to the sensibilities of the urban liberal. Not that there's anything wrong with being an urban liberal, of course. But this demographic also happens to be blessed with the financial means to ensure that NPR remains a vibrant source of news.
And it is nearly unimaginable that anyone on the left would support subsidizing programming imbued with even a subtle right-center bias. Let's be honest; if NPR weren't substantially left-leaning, Democrats wouldn't be such huge fans of federal funding. The rest of us can listen to, say, Nina Totenberg's slanted dispatches with the appropriate filter.
"Urban liberals" and people out here in the boonies who want to be like urban liberals.