Not that simple
@James O-Brien: "Why is it that Apple and the book publishers are being offered a free pass here?"
For a start, there hasn't been an investigation or verdict in this matter. Microsoft and Intel were first found guilty and then punished accordingly. The EU and US anti-trust bodies are voicing concerns that this behaviour *might* damage the market, but not that it *has*. If the concerns are addressed, the market is protected.
Secondly, this market has already been subjected to questionable behaviour by Amazon. It seems people have short memories - with at least 90% of the eBook market, Amazon first tried to strangle the existing (paper-based) book market and then to hold the remainder with an iron fist, e.g. http://www.nzherald.co.nz/technology/news/article.cfm?c_id=5&objectid=10791546
Amazon tried to strong-arm publishers into exclusive agreements when Apple first made moves to enter the industry. Anti-trust action would certainly have followed if arrangements between Apple and publishers had been blocked by Amazon. Stating "you can't sell through anyone but us" is far more damaging than stipulating "you can't offer competitors a lower price than you offered us". This is still a (relatively) young market. Now that we have more than one strong player, I think the anti-trust measures are enough to ensure an even playing field.