Apple - How can I detect in activity log if 'PC repair shop' guy had a look at my files
In short, if they really, really wanted to look at your data, they could do it in ways that you could not detect.
What generally happens, though, is that these professionals - whose job relies on their reputation & integrity - simply couldn't be bothered even checking to see if you had anything more interesting than a couple of dodgy torrents.
It's very common for PC techs to search for erotic content. PC techs are very practiced finding hidden folders and files very fast. They hope to find your girlfriends and other original content. And it's also legal to do so for them.
Can A Computer Store Tech Look At Your Files?
Declan McCullough is discussing a recent lawsuit where a guy brought his computer to Circuit City to have a new DVD drive installed. The technician who did the installation then wanted to test it out the software that came with it by playing a video. The tech found a video file on the hard drive and played it... only to discover that the video was child pornography. He called the police and the guy was arrested.
See also Computer IT people could face fine, jail time for not reporting child porn.
A Utah lawmaker is proposing a bill that would hold computer technicians liable if they see child pornography on a client’s computer.
There is no way for you to detect that when your PC tech understands some basics.