Ignoring the question of why it’s Apple’s job to prevent their customers from breaking AT&T’s terms of service, it’s interesting to note just how much this policy is centered on the United States. The iPhone is sold in dozens of different countries and works with dozens of different cellular carriers all over the world. You can be certain that each one of those carriers has different terms of service. Why is AT&T so privileged that their terms of service, and theirs alone, are the ones that Apple looks at when deciding whether to reject or accept any given app? It’s quite likely that people all over the world are missing out on great iPhone apps that their cellular carriers would permit them to use just because AT&T does not permit Americans to use them.
This by way of saying, for example, because AT&T prohibits SlingPlayer from running over 3G, users in Canada (on Rogers), the UK (on 02), Japan (on SoftBank), etc. are also prevented from using SlingPlayer of 3G.
Apple certainly makes only specific mention of AT&T in their consideration process. However, AT&T was the first iPhone carrier signed, so perhaps there's something in that original deal that makes it so -- or is it just that Apple is headquartered in the US?
Now, presuming those other, international carriers aren't just sighing in relief that AT&T takes the hit on this so they don't have to (anyone think Rogers, O2, SoftBank, et al. are dying to take the network hit that comes with an uber-popular, functionality surfacing device like the iPhone doing high-bandwidth tasks like streaming TV shows and movies?
There are certainly examples enough of region-specific apps (AT&T's own apps are just in the US), and apps that are missing from just one regional app store (Skype is not in the Canadian App Store, reportedly due to a patent dispute).
As mentioned previously, Sling has submitted a 3G-enabled version of SlingPlayer for non-US App Stores (Canada, UK, Japan, etc.), so we'll soon see.