a cosy arrangement
I remember back in 08 when i used to work for one of the large publishers, the absolute confusion as what to do with ebook pricing, when the sony eReader came along.
Should they reflect the hardback or the paperback price was the question... As ever the bean counters were so terrified about protecting revenue and undercutting their existing products as they saw it.. they opted for the HB price, and in one stroke killed the publishers credibility.
This is why ebooks were priced at the same value as their hardback versions i.e 20 quid for a great tome= your azw or epub.
It's all about protecting profits and keeping the cosy publisher vs author relationship in check.
I'm certain the other big publishers followed suit, hardly a co-incidence they all adopted the same pricing strategy!