I actually allow mice to live in my garage, because hey, it's not very nice to kill living beings. If they were in the house, then I would consider them a health threat and would reluctantly eradicate them. In the garage, they occasionally chew up a glove or an extension cord, yet remain primarily harmless. I let them be. But I can't very well drive to work with one perilously near a vent fan; if it died I would feel kinda bad and it would cause that yucky death stench. I took the car instead.
Now I suppose the mice have become enough of a nuisance to bother trapping the poor creatures, but I'm gonna try to trap them live and incarcerate them. The tiny crimes they have heaped upon me over the last several years still fall well shy of the death penalty. And besides, they're just so cute. You know, same reason I can't kill Sailor Scouts.