[silversnitch]

In my case they ran a diagnosis over the network to make sure everything is working.

Diagnosis software is built into iPhone so I can put a trust on it that it ain't sharing private data to the store employees.

Similarly they ran a diagnosis again at the end of repair. They did boot up the phone my themselves and ran it. Looks like they can run diagnosis on locked Phone.

This is overall much better than asking to unlock Phone.