I never saw a small "mom and pop" bookstore that could match Borders or Barnes and Noble for selection.
Kepler's in Menlo Park came close at one time, but these days they're less so. They're not quite a mom & pop anymore either, but they sure started out that way, and I believe they're still local-only, too.
Most of the Barnes & Noble's around here have gone downhill, imo, since they started expanding/opening up a whole bunch of new ones 10 yrs ago or so. All the new ones feel too small and the focus seems further & further away from fiction books. I used to love the B&N in SJ near 280. Still the best one in the area imo. But still also not as good as 15-18 years ago. Borders ... meh, I never liked them much. If they were around and I wanted a popular new-release book, they were fine, but otherwise...
I'm glad I don't read as much anymore. I think I picked a good time to stop being an obsessive fiction reader. This era of digital books and purchase-everything-online is not for me. And yeah, this kind of thing will eventually limit a lot of retail/service jobs. It'll be interesting to observe.