Most bookshops do, in fact since Amazon/abebooks/etc most used bookstores do <50% of their business through the door. They make their money on Amazon, others don't even bother with the store anymore - they buy job lots of books put them in cheap warehouse space and sell them for 1c making money on the s+h
This guys trawls library sales, thrift stores etc. Library sales are normally run for charity and everything is 50c, the librarians have already selected the books to go into the sale so there isn't much chance of a $100 book being found. The aim of 'friends of the library' group of little old lady volunteers isn't really to invest $1000s in high tech to make a little more money.
Sounds like a business opportunity. If someone wants to sell a bunch of books, they hire you to come scan it for valuable ones, sell them on Amazon and split the revenue. Then they can donate the rest or sell them for 50c. It benefits the seller, because they get into the Amazon market without investing in learning/equipment. It benefits you the arbiter because you get exclusive rights to the books, shutting out your competitors.
Presumably the library already has the ISBN of the books it is getting rid of.
They could pull out the ones worth >$1 after checking on Amazon and then package and ship them - but thats probably not cost effective for a library employee and getting little old ladies to spend the day packaging and shipping isn't what they volunteered for.
They could get in some minimum wage temp labor to do this once a year - but that's not really the libraries core business. It would be like having police patrol cars pick up cans by the side of the freeway for the 5c recycling (now theres a business model)
This guys trawls library sales, thrift stores etc. Library sales are normally run for charity and everything is 50c, the librarians have already selected the books to go into the sale so there isn't much chance of a $100 book being found. The aim of 'friends of the library' group of little old lady volunteers isn't really to invest $1000s in high tech to make a little more money.