- No one remembers when they replace batteries and they don't leak.
- Everyone remembers when they replace batteries and they leak and damage something.
- Duracell and Energizer are the most widely used brands.
I suspect the leaks are statistically insignificant, and only happen due to imperfections in manufacturing process and natural statistical variance. If you could find a way to measure the internal pressure of the cell, that would be very interesting to see.
I found a book called "Battery Hazards and Accident Prevention" which claims alkaline cells may develop internal pressures of several hundred psi
That explains the others here who have mentioned the AAAAs in 9V batteries exploding, and I've personally experienced an AA pop its seal while I was there, minutes after it had been rather abusively drained at over 3A (it sounded more like a very loud balloon popping, followed by a bubbling sound as the electrolyte poured out.)
Thus, discharged cells are already under high pressure, and I guess over time the seal just deterioriates and allows them to leak.