How in the world can the supplier be responsible for an item that they shipped and was marked ‘delivered’ at your door by FedEx?
As far as the nice area you live in...In my business I’m constantly doing work in upscale neighborhoods and there are more garage and porch thefts than you would ever believe.
It sounds like you are hurt by the fact that the company you give a lot of business to, won’t take care of you on this situation and I totally understand that but that’s a judgment call on their part.