A rural bookstore won't have sufficient density of local customers to be viable. They need to make additional sales from somewhere. That "somewhere" has to be m

A rural bookstore won't have sufficient density of local customers to be viable. They need to make additional sales from somewhere. That "somewhere" has to be mail order, where they maybe could be competitive due to lower costs. But now they can't actually compete. (This is all purely hypothetical, and explaining how the statement could be true. Probably it isn't, since there's no way an indie bookstore competes on price with Amazon.)