OK, well you asked what I thought to be good-faith questions and I’ve given you good-faith answers from my understanding of common law.
Given those answers, I’m not sure what you dislike unless you think the electrified sign is not dangerous or deadly. That might be possible, but as I said, the law generally frowns on devices rigged to harm. It’s an issue of unlimited justification of bodily harm to protect property which, as I said, has been hammered out in common law over the centuries and I think is generally reasonable and good.
So would you rather the property owner had shot and killed the trespasser as is allowed under the laws in some locales? (very rhetorical)
...unless you think the electrified sign is not dangerous or deadly.
Ah, the stipulation amongst carefully chosen words!
Dangerous? (able or likely to cause harm or injury) To a small degree it is. Many things in life are "dangerous". Do you still pick blackberries despite the danger of the thorns? (rhetorical)
Deadly? HA! Even small animals are not killed with such systems.