These ads are made months before the product is released, and often the team making the ad does not have physical access to the product. Even if they could get access it is standard to use stock photography to keep cost down and get the ads turned around quickly. For the same reason restaurants use stock photography instead of taking their food to a studio or any other type of marketing
This. Why send your device out with a photographer and hope they can get a compelling image when they can browse thousands from a stock photo outlet and get something perfect in an afternoon? The stock photo will be much cheaper as well.
Well, for one thing: because then you don't get a bunch of viral news stories floating around saying stuff like "Samsung couldn't even use their own cameras to do their marketing." For another, because it sends a strong message that your phone cameras aren't up to professional quality standards, despite the fact that they might well be.
I wasn't aware of Apple's example; that's Apple being smart, not Samsung being stupid. Stock photos being used for simulated product images has been common nearly forever.
I'll agree that maybe the time has come for that common practice to be changed. Camera companies put prototypes into selected professional's hands to get early feedback and images, maybe the phone companies should do the same.