I think this may be because of bug http://feedback.dayzgame.com/view.php?id=8809. Loot in general is very hard to find in houses - it may be that can openers DO spawn, but since they are relatively rare, and you can't see most of the loot in houses, we simply don't run across them.

I know I have found ONE can opener in a civilian building. But only the one.

@Geez hi :)

May be close this ticket like obsolete?