Fair enough - they should go after Sony as well, and they likely will at some point.
Two totally different business models and markets.
Sony and MS make less than brick and mortar stores do in most cases selling digital downloads. It's not at all the same thing. They are essentially online retailers the same as Best Buy, Target, or Amazon.
Anyone can buy digital download codes from Target, Best Buy, or a physical disk (and they make 30-50% on the disk sales, more than the digital sale in many cases) and redeem them for download on their console or buy physical media. There is consumer choice at ever level. There is none in the App Store.
What Apple is doing is essentially charging a 30% transaction fee more akin to a credit card processing free which is usually only 5%, and they are not acting as a reseller. They are also the only "seller" in regards to a paid app. Because Apple does not allow you to obtain the digital goods in any other way, this is where they are being anticompetitive. They impose their own requirements on the developer as well. When you buy an game from Sony, Microsoft, Target, Best Buy, etc., that 30% is a mark up that nets the items margin and then they eat the 5% credit card transaction fee out of that margin, and eat 100% of the cost of any returns in most cases where Apple charges that back to the developer.
Apple could just as easily allow you to purchase a code direct from the developer or a third party reseller to redeem for an app or add on item like gaming does, but they do not.
I can see where people don't connect the dots in how its different because it sounds the same, but when you drill into the details its totally not at all the same.
BioWare sets the wholesale cost of a game at say $41.99. Microsoft, Target, BestBuy all sell the game at the MSRP of $59.99 netting them the 30% margin, and usually have a contract with BioWare to not sell below MSRP for the first 60-90 days after the game is released.
When you see Microsoft and Sony having a sale, sometimes that game is getting a manufacturer's subsidized discount, and other times, Microsoft and Sony are just making 10% on and reducing their margin, the same as Best Buy does.
The only thing that is truly the same is that with MS and Sony, it's digital goods and not physical goods. The business model is very much the same historic model goods have had since the first store opened its doors thousands of years ago.