There's Always a Bug
Sometimes the bugs make no sense, at least not to anyone who isn't looking at the code. Take this one, reported from Australia this week:
BOQ's Eftpos machines skipped ahead six years when the clock ticked over to January 1 and started date stamping January 2016.
I can't really laugh that loud, because the archive bug I used as a launch point for this post earlier in the week was pretty stupid, and - to anyone but me, who wasn't looking at the code, inexplicable - archive links worked for any non-2010 date :)
Sometimes, developers toss in code "that's good enough for now" - leaving a grenade that explodes in someone else's face later. I'd bet good money that the BOQ bug is like that.