> Why do they need to verify my role?

Because people lie, constantly. And while most of time they they might not be, it happens often enough that companies pay people to background check applicants. It's not good, but it's seemingly necessary, or at least desired.

> Also, there isn't senior at Apple and their roles are not a public API. They can change. If Apple says my role was "level 5" what does that mean to the new company?

Dunno, but a hiring manager for a tech firm probably knows better than me or you. Either way, obfuscating your previous role isn't a good thing.