I have personal experience with this an I'm not sure deciding something should be illegal based on one experience with your brother is the way to go? i recently bought a collar for my dog and am only using the vibration setting but will use the static if i absolutely need to, my dog is a hunting breed and we're moving to a rural area, if he gets out he will absolutely kill sheep and i dont want this for the sheep or my dog to be seized by the council. I'm highly experienced with dogs, work in rescue and do not think these collars are for everyone or should be used often, but they are definitely effective in some situations where the life or death of an animal is at stake. Maybe they need to be licensed or something, but i dont think made illegal xx
Oh also I've tried the static setting on my own arm and it's very much not what you expect, nowhere near as bad as its made out to be. I think the main reason a dog would react to it is because its a surprise to them, not because it hurts them