I was going to ask the same thing. I have had numerous leaks - kid's remotes, torches, bike lights, the usual common denominator is that they had been left semi-depleted for a while but that is not always a factor and I have just opened a 2 D cell incan with old batteries that has been lying around for a couple of years with no leak.
I think it is partly luck and a numbers game. If you use them fast and change them out you might lead a charmed life like McNair55, but if you leave a few devices around with used batteries for any length of time sooner or later you will have a leak.
Best option is to go NiMh, alternatively removal & storage of batteries after use which is what I try to practice when I remember.