Intention is relevant. What if I was mentally ill and mistaken your backdoor for my own? Or it was was the only feasible escape route from a murderer that was in pursuit of me? Of course this doesn't apply directly to the OP, because this house analogy doesn't hold water. BUT, intent is very relevant when it comes to law.

Well, no, intention is not relevant in the sense that these people are still trespassing. Ok though, you have a point; in some extremely rare circumstances it may make a difference. Of course, as you said, none of these apply here, so what's your point?