It’s pretty much impossible to move a tank anywhere without it pointing at something or someone. You can’t exactly point the barrel straight up or down to the ground. I imagine it’s probably a bit harder to accidentally fire a shell than the trigger mechanism of a firearm.
That’s probably a good thing, otherwise your tickets would probably be 3x more expensive. They pay for your ferries that you rely on.
Ferries are the main reason I would never consider living on the island.