Part of the problem here is a change in tax law a couple of decades back where the backlist as a bunch of printed books in a warehouse became a tax liability when Congress tried to close a tax loophole which non-publishers were exploiting.

Rather than the old model of printing a reasonable print run, selling books as demand allowed, and keeping unsold books in warehouses only paying tax as they were sold, the new laws required paying tax on inventory each year --- so any books not sold in the first year were not as profitable, hence book remaindering, and the current mess.