The usual reasoning behind this is to confirm the phone is properly functioning before opening it up.
Lots of people try to scam repair shops bringing broken phones in.
On top of that repairs can often break fingerprint scanner connections and depending on the screen type its good to check camera functionality after screen replacement.
In my case the screen didn't work at all. I couldn't backup the device, log out of any accounts, etc. I still wouldn't have given them the passcode if I could have done that, but if my only option were to backup and wipe the device before the repair, I would have reluctantly done that. In this case I had no way to secure the device at all, and I couldn't wipe it remotely because the only critical thing on it was my TOTP app (which I've since replaced with one I can sync/backup).
Of course they can, but that means having the user come in to unlock the device and potentially sending them home again if you have to do additional repairs after testing it with them.
It’s all a balance of convenience vs privacy. Best solution is to wipe the device before repair, which is what I have done every time but it’s a hassle even when I have a backup to restore.
Lots of people try to scam repair shops bringing broken phones in.
On top of that repairs can often break fingerprint scanner connections and depending on the screen type its good to check camera functionality after screen replacement.