> Apple has already been doing exactly this for years.

Is that an assumption made based on that "everyone is doing it" or is there some evidence?

> Apple makes the OS and doesn't need a fancy system to scan all the files on the device if that's what they want to do.

If the goal is to scan all the files on everyones device this system is exactly what they need. It's not like they could upload hashes of every file on every users phone continuously.