I've done it myself. My neighbor gave me an old Kodak folding camera. The first thing I did was to wind it and open the back. Only to find there was a film in it. Granted, it was no loss as it's been stored in HOT Florida attic for decades....

It's just a common reaction to want to twist knobs and push buttons.... People aren't used to film cameras anymore, either - regardless of their age groups. Only thing you can do is either not hand someone a loaded camera or say "don't do anything, film is loaded" before handing it over.