I some problems with a pack of 4 Napolina chopped tomatoes some months back. The ring pull snapped on every can and I had to resort to a tin opener.

I usually use a hand held electric tin opener but, otherwise, I do have a couple of (smaller, I don't like the really thick ones with 100s of blades) Swiss Army knives and can use the tin openers on them if I need. I don't think my left handedness helps me in working out which hand or orientation I want to attack the can with but, that solved/re-remebered, I find them quite useable.