To be fair, the amount of data a service person has when they have your phone or computer is incredible. If you keep a bunch of nudes or anything sensitive on your devices, chances are the service person will have seen it unless you are particularly good about hiding them. Sure, Apple shouldn’t be forcing where you get your device fixed, but the fact that so many people know so little about their devices makes me concerned, especially when they are looking for the lowest deals on a repair. There’s no way for the average person to tell if their data has been collected.
That being said, it’s still quite a bit of a stretch for Apple. Any service person, including their own Geniuses, could potentially steal data.