I've got nothing against mom and pop stores in principle. But to ascribe to them some mystical virtue is unwarranted. If they really were "better" than Wal-Mart, people would keep patronizing them. And some such stores do survive.
The anti-WalMart thing really is liberalism at its worst. Some people cannot stand the fact that their fellow citizens make free choices with which they disagree. If someone decides to withhold their patronage because they don't like Walmart, that's fine by me. It's when people think "something has to be done about WalMart" that I start looking for the commissars.
Nor do I, and all things being equal, I always pick them. But not because I'm someone's idea of a patriot.