These new rules were not made specifically to pressure Amazon or Netflix because Apple as similar offerings (iBooks, iTunes). It is Apple´s way of testing if they can get away with getting a share of the revenue stream generated on their platform.
No, neither. It is their way of making sure they get compensated for the cost of the store. Same as the 30% on straight-up app purchases.
The zero fee alternative offered by so many MacRumors
economists would mean that every developer would make their apps free with no functionality. Which could then be purchased via IAP, bypassing any fee whatsoever to Apple, causing Apple to eat all costs of the store, even though they sell very little in it themselves.* Apparently, they decided the best solution was to include IAP purchases in their 30%, which does seem like an obvious solution. (esp considering antitrust issues, which makes all these comments rather hilarious) See, they aren't morons. If anyone else recalls, there was no store at first, Apple started it up by popular demand. A particular aspect of their business where SJ was proved 100% wrong, and changed his mind. But they are going to run it like any other store. Walmart makes money, BestBuy makes money...they know how to run a store. Apple seems to be doing ok, also.
I'd like to hear someone's 3rd option, since everybody knows so much.
* side point: this would likely mean the eventual end of the store, too. I wouldn't want to purchase my apps that way, it would become tiresome and I'd leave/jailbreak/whatever.