The Hallowe'en, trick or treat thing is mainly a US phenomenon although it has filtered back to the UK through US TV shows. In my youth, 60 plus years ago in the north west of the UK, it did not exist. We had bonfire night five days later. This was a big thing and had it's immediate roots in 17th Century UK politics and probably pagan roots before that. Any reality concerning those pagan roots would have been suppressed by the Church of course. Smoke has well and truly gotten into our eyes.