Because repoing a car is a risky venture. It is not uncommon for repo men to be assaulted and shot at it. It tends to happen more in lower income areas.
Also some neighborhoods do have a higher crime rate. If a neighborhood is known to be violent, and you are going there to take a piece of property, it increases the chance you will meet violence.
Here's my credo: There are no good guns, There are no bad guns. A gun in the hands of a bad man is a bad thing. Any gun in the hands of a good man is no threat to anyone, except bad people.