Testimonials reflect the market?

We hear testimonials to the wonders of WUNC now and again by people with names that are largely unknown but who, in the end, don't strike me as reflecting very well the diversity of the geographic market that WUNC covers. I wonder why that is? It's pretty easy to figure out, and seems to reflect only a sense that the station is the preserve of a club of well-educated and often rich people who see it as their toy.