While I used the wrong terminology in saying they lost the trademark. They filed the trademark and before it was approved there was extensive litigation over the matter with apple suing different companies in many different countries over their use of App Store. Eventually apple realized it was likely going to lose and settled its case with Amazon letting them use the term. I agree that it would be very difficult to get App Store approved it wouldn't have been impossible just because app had been around prior to this. Think of sportsmans warehouse. It is likely a a valid trademark even though it could also be seen as a description. Another sportsman couldn't open a warehouse store and call it sportsmans warehouse. But you are right that apple would and did have a hard enough time with it that they eventually gave up and likely would have lost.