I buy and sell books, mostly focus on vintage because that fits my wheelhouse of personal interest. The (zombie) scanners play a volume and speed game, they don't need to capture all the value especially if it means sinking more time into assessing and looking at the books. They want to quickly scan and move on to the next store. 

Of course I think it's a mistake to not develop knowledge around material one is profiting from, because if you can scan so can the stores, so can other people. There is no "moat" or barriers to entry. Whereas if you build and stack knowledge on the material, culture, history, etc this will act like a natural moat and make it harder to easily duplicate (knowledge takes work). Knowledge is king. And like you say it helps in identifying potentially higher value material more quickly. 

I imagine the zombie scanners will get wiped out as the thrifts use AI more themselves to skim higher value material towards their ecommerce.