Overpriced books have exactly zero to do with anything. Books are still selling in huge, huge numbers, and as long as a product is selling, you can't blame the price of that product for failure.
And, no, it is not incentives that get books into stores. I don't think you understand the book selling business at all. Chain bookstores have nearly always dictated everything to publishers, not the other way around, and chain bookstores Must Have Books To sell. Period.
They take as many as they can possible display, and always want more. They want so many that few have the chance to remain in the store for very long.
Publishers very, very seldom have to offer any incentive to make bookstores take books. Bookstores either take books, or they don't have a product to sell. Publishers offer incentives for special display space, usually for books written by bestselling writers, but little else.
And your reason is dead wrong behind even this. Chain bookstores have had publishers by the short hairs since the beginning. It's simple. Publishers need bookstores more than any bookstore needs a single publishers. Chain bookstores make a LOT of money, and a heck of a lot of profit off books, but they can also more or less blackmail any given publisher. The bookstore can always get books, but a publisher can't get a bookstore unless the bookstore says they can come in.
But it's just wrong to say a product us overpriced when so many sell. Demand always dictates price, and the reading public is still buying books in incredible numbers. If the reading public stops buying them, prices will drop. Until then, prices will, and should, remain high. No business is going to sell something for a dollar when people are willing to pay ten dollars. Right now, immense numbers of people are paying the current price for books, and continue doing so year after year.
So they are not overpriced.
Chain bookstores, some of them, have failed purely and simply because of over extension in bad times, too much competition willing to undercut them, online bookstores such as Amazon, and some incredibly stupid business decisions, which is why Borders died. Amazon has given many bookstores fits, but Amazon is a brick and mortar bookstore, it's just one that sells online, rather than having people walk in.
E-books still make up a small percentage of sales, and even most e-books are sold through mainstream publishers, and are written by bestselling writers.
Warehousing is a publisher problem, not a bookstore problem.
The giant chain concept was never a good business model for more than one or two chains. It isn't the best, even for one or two, but the current price of books has nothing at all to do with it. To make it a good model, the price of books would have to be considerably higher than they are now.
As for help, there is no better help in a bookstore than youngsters and students. Even if you could pay higher wages, these are still people you would hire. Selling books is not rocket science, so hiring rockets scientists, along with rocket scientist wages, to do the job would be silly.
McDonald's makes billions in profits, but they hire youngsters and students, at low wage, because these are the people most qualified to do the job of selling burgers. Do not expect them to going looking for better help at higher wages anytime soon, no matter how much profit they make.
Now, it's true that independent bookstores are seldom located in high rent areas, but this is simply smart business, something most of the chain bookstores seem to have no clue about.
And most bookstores owners I've known, especially the successful ones, do not rent, they own. Renting always puts you at risk, so the choice of renting in a high rent district, or owning in a cheaper district, is a no-brainer.