"Yup, however if a file name or image is seen that is suspicious"
File name, maybe in limited curcumstance. Image - why are you looking at images on a customer's computer?
Let's presume the customer to be innocent of anything, an old-fashioned assumption admittedly but an essential one if we wish to live in a free society. So what might be on the computer? All manner of personal stuff if it's consumer machine, all manner of commercial material if it's a business computer.
The default assumption must be that it's confidential to the owner and/or user. In the case of personal stuff, at least in Europe, it will arguably* be protected by existing personal data legislation and even more so under GDPR. In the case of a commercial machine there's likely to be commercially sensitive material on there, some of it subject to various regulatory regimes: financial, medical etc. To go poking around in contents, even listing file names, of anything not immediately relevant to the work that's being done is at minimum a breach of confidence and quite possibly a breach of other legislation or regulation.
TL;DR A tech has no right to go poking around in the PC's contents.
* There must be an argument that anyone accessing a PC is at the time the processor of any day data file they open.