"locks that need replacing. why do they need replacing? because they failed?"
Umm, yes. Why would you expect a mechanical device which is left exposed to the elements and is almost certainly never given any sort of maintenance, not to fail at some point?
And then there's the rather healthy business of selling new locks to people who've just moved house and would prefer not to trust that all copies of the existing keys are now in their hands, people who've extended their homes and now have new exterior doors in need of securing, people who've lost a door key somewhere and would prefer not to hope that it's either never ever found or is only ever found by someone sufficiently trustworthy to not do anything dodgy with it, people who're replacing older less secure locks with newer ones...
No, can't think of any good reasons why lock companies manage to stay in business, guess they must all be up to no good eh.
Biting the hand that feeds IT
