I'd be afraid to drive behind vehicles with trailers where you live!
I've had a trailer pop off the ball once, the bolt that holds the coupler in was loose and fell out, luckily I was on a road in the middle of nowhere, It just came off the ball and dragged behind me. A friend of mine wanted me to haul it to his new place.
Yeah, so many things that can go wrong in the system. Hitch pin can break/fall out, ball could break/fall out, socket could come off ball...
Neni, usually the chains are mounted back about 1' on the tongue, either welded or bolted in place. On the vehicle they attach to holes beside the receiver so they're completely separate from the ball system.
The entire hitch assembly, or the entire tongue on the trailer would have to come off for the system to separate!