NPR/PBS, reliant as they are mostly on voluntary public donations, is a mere shadow of the legislatively-created and taxpayer funded BBC in the UK (or the Australian equivalent, ABC, for that matter). A poor cousin at best. You can't compare them like that, it's chalk and cheese quality-wise.
Not many people see PBS as a high quality or popular channel in the US. But, in Australia the ABC is one of the most-watched and best-quality networks (and has multiple channels in most areas). Ditto with the UK and the BBC.
I think your confusing quality and quantity of programming... yes the BBC has what, 4 television channels along with 5 or so radio channels and as such it is a MUCH larger organization than NPR/PBS, but PBS still produces NOVA, Frontline, Charlie Rose, and the News Hour with Jim Lehrer which is in almost every case higher quality programming than ANY of the "major" US news networks (not even to mention they also make sesame street and antiques roadshow, which have been a cornerstone of entertainment for our country's young and old for decades). NPR also is an invaluable news source, it is a great place to turn if you want actual news presented in an educated well researched manner. Their news stories are relevant, factual, and don't pander for ratings. You are correct in that most Americans don't view NPR and PBS as popular stations, but this has NOTHING to do with the actual quality of the programing. It's sad that people prefer the sensationalist crap that is FOX first and foremost, but all major networks are guilty of to some extent.... just please don't relate people's preferences to quality, because at the end of the day we do still live in a country where NASCAR still claims to be the most popular spectator sport...
Is your job running? You'd better go catch it!