Some people might not have room in their truck for a dog and can't afford to get a better vehicle more suited to the dog, so their only option would be to put the dog in the back. I don't agree with it but there are certain circumstances where there isn't much of a choice, in my opinion. If the dog is tied on a *short* leash inside and can't jump out or if s/he is in a crate strapped into the truck (I feel much better about the crate idea) then I'm alright with it, but still don't really like it. I cannot stand to see dogs secured but on a long leash that they could hang themselves with if they were to jump or not secured at all.