Them dang bears in the mountains around here (where we most often camp) don't care at all about alarms or lights!
If a cooler is left out where they can get at it, they will tear it open and find whatever is inside.
If they smell the bacon you cooked for breakfast, they are quite capable of tearing the side of the trailer off to get at it.
No, it doesn't happen often, but it has happened.
I don't much worry about people, it is the four legged critters that concern me. There are some mean ones in them thar hills!