I've emailed Sony's support department. Their stock answer is what I expect, which is, "the publisher sets the price". Nor will they match Amazon's price. Amazon gets better pricing because they "license more copies" than other vendors (according to a previous reply from Sony).
So, yes, e-book pricing is a big mess, because of the way publishers "license" "copies" to retailers, who discount, or not, from there.
But keep up the pressure. Email Sony and other vendors every single time, because I believe the issue will work its way back upstream to publishers, who will one day understand that
1) It's silly to price and sell digital stuff the way we price physical stuff and
2) Letting Amazon rule the world is, in the long run, bad for business.
Also of note, down at comment #198.