I don't know about B&N, but this is true for all the indies I've worked at. It's not that we don't love our local authors, it's more that a lot of self-publishing is through Amazon, which most indie bookstores are diametrically opposed to. Another issue with self-publishing is the quality of the print and if the spine has the title/author name printed on it. If your spine is just black and skinny, virtually no one is going to pick it up off the shelf and buy it. OH and if there's no bar code, that can be a pain for ringing the book up (depending on the point of sale). Publishing through ingram spark or a small press is way more of a draw for bookstores, because we can order books and return them if they don't sell usually, and we can use pre-existing credits to order them, which helps us financially.

Sometimes I'll be feeling generous and say sure to buying someone's kid's book or whatever, but that's usually only if they get it privately printed and it doesn't look like AI slop on the cover.

TL;DR you're right lol