I've been around electric fences for around forty years now. Have miles of the stuff. All they need is a deer or a tree limb to get grounded enough to shoot out sparks. If it's on a charger worth having anyway. Always a piece of wire working out of the ground somewhere on an old fence line, usually steel posts, even a rock with sufficient iron content. Have seen several fires started in such a manner. When you see a burnt place and find a short in the fence it is pretty obvious what happened. I can totally understand why they might be illegal in places that have trouble with brush fires. Everybody might not have a tiny chicken fence that they can see the entirety of from a bedroom window, in order to keep it maintained.
Have also trapped many coyotes that were crossing electric fences. Have seen tracks in the snow, they either jump a low spot, or just hit it at a run and pop through between the wires. This in country where there are a lot of electric fences, and where coyotes that were afraid of electric fences wouldn't survive long. Have chased coyotes with hounds and had the coyotes use the electric fence to throw hounds off their trail. If you want an electric fence that will keep coyotes out, you better have the only electric fence around, or have a lot of wires on it, with some of them grounded. A fence like that can be challenging to maintain if it is on much of a scale. Electric netting is good, but most of it is short enough that coyotes can jump it without even breaking their stride.