I believe you're right, I never did get to participate in trick or treating during my time in the states, I was too old and lived in quite remote areas. It wasn't really a thing here in the UK until the late 80's being something of a US import.
Yeah I've heard tell of fucked up shit like that along with poisoned candy and marijuana edibles added into kid's baskets. Unbelievably fucked up. 😑 I may have a few halloween pranks up my sleeve but anything in the vein of harming kids really does make my blood boil.