Just because locks have existed for thousands of years doesn't mean they are used everywhere. When I lived on the countryside in Australia we didn't lock the doors. That's not "an extremely long time ago" ;)

> When I lived on the countryside in Australia we didn't lock the doors.

Well of course you don't; the robbers die while still crossing the perilous deserts and/or trying to avoid lethal wildlife.

> That must have been an extremely long time ago: http://www.ancientresource.com/lots/roman/romankeys_locks.ht....

Nope. I can tell there are still people alive these days who remember that this was still the case in most places of Western Europe.