The more taxes are cut, the more people complain about how high they are. If you want to see high tax rates to back to the 1950's. If Amazon could raise their prices and get people to pay the higher price, they would have done so already. Competition limits the ability of companies to raise prices - if one company raises prices, the competitor stands to gain by not raising prices.
Of course, this whole conversation really has nothing to do with Amazon and certainly has nothing to do with e-books. I'm surprised it has remained in the e-book section this long. Perhaps the OP should take all this energy to lobby to change the law.