Upload & Sell: Off
It's happened with 3 different cameras, and 3 different cards. Now, I doubt the lens I was using had anything to do with it. Nor whether I had bacon or sausage links for breakfast.
That is some terrible, terrible luck right there... but it's not representative of the bigger picture. If your experience were typical, or even slightly common, camera manufacturers would be removing the function from their cameras, because the entire market would be saturated with people losing their entire card contents. Deletion is a super simple, safe process that doesn't even actually remove much data from the card; it simply removes the header and marks the contents of the blocks as eligible for writing.
I do see, though, why you would be gun shy about it.