I worked as the store manager of an indie shop for a few years after running their online store by myself.

Abe hardly benefits the actual book shops. It's crowded with megasellers, just like Amazon is. I would say half of listings on both sites are by HalfPriceBooks or Goodwill. Most sellers who move over 1,000 books a year online will use an automatic listing service like Neatoscan that posts on Amazon and Abe (and like 10 other sites) at the same time.

If you want to benefit actual book stores, buy from their website, call them and buy over the phone, or go visit them in person. Bookshop gets an honorable mention, because they share 30% of the profits with the book store while hosting the site and storing the books and doing the shipping. It's incredibly generous.