>>> "As long as the developer distributes the appropriate licence text with the App, and details of where to get the source from, then Apple?Microsoft/Google/etc would be fine."
>> Actually there appears to be some debate over that. I for one don't blame any of the 3 companies above for not wanting to be a test case. And the "foaming at the mouth" tone of your reply here rather supports the point that there are some people out there who really dislike Microsoft (possibly with good reason, fair enough) who would make a point of chasing them on this.
It doesn't need a test case, you can read the licence for yourself - it's not hard to understand. Even if a developer did upload some GPL software without the correct licence attribution etc, FSF wouldn't be threatening them with court. FSF would be asking them to remove it (or arrange for it to be brought into compliance). Only if the app store operator refused would the legal threats start. That's the way the FSF work. The legal risks of allowing GPL (or other free licence) software into the store are really negligible.
To put it in perspective, any one of the program that has been allowed could be the subject of (for example) a patent infringement claim. And of coruse, any of the other programs could be in breach of some other licensing issue (eg ripped off code). On that basis, the store wouldn't allow **ANY** program in because it's a risk. So the risk of ending up in court for allowing GPL code would be no more (and probably less) than for stuff they already allow.
As for foaming at the mouth, well I'm not the one spouting all the BS that it's impossible to comply with GPL3 while distributing stuff via an App store (whether Apple, MS, Google, or anyone else's). The restriction is entirely non-technical, and is entirely of the app store owners making.
Apple could distribute GPL3 apps via their store without falling foul of GPL3, as could MS et al. They have chosen to apply digital handcuffs to their users, and GPL3 is incompatible with that entirely political/commercial restriction the vendors have applied to their wares. The question should not be "why is GPL3 incompatible with <insert vendor>'s app store ?", it should be "why do people accept such restrictions from <insert vendor> ?".
So all this "anti free software" really is blustering and FUD on the part of the vendors for whom the idea of end users being able to choose how and when they use stuff they paid good money for is just that - blustering and FUD.
Personally I'd like to see these restrictions tested under the UTCCR regulations - where I think there's a darn good chance they'd be declared illegal.