Why don’t publishers allow purchasers of print books to obtain an electronic copy that is included in the price of the print edition?
At present, I know of no movement among publishers toward such a possibility, and I seriously doubt that publishers will ever allow such a mechanism with regard to mass market paperbacks. Given the economics of publishing, some publishers might theoretically consider providing an electronic copy with the purchase of a hardcover, if there were some way to ensure that the electronic copy remained with the purchasers, but the problem with that is that there’s no way to do it, and given the current tendencies of all too many readers, a sizable fraction of purchasers who obtained both might simply transfer the electronic copy — or the hardcover — to someone else, thus further cannibalizing already declining sales numbers… and that’s something that no publisher wants.