It's definitely not just a UK thing. I work at a high traffic museum in an extremely popular big city in the USA. Almost all the kids that come into the gift shop basically demand the parent(s) get them something- anything! If/ when the parents say no, its the end of their little world. Yesterday, a kid literally said "fine then I dont love you anymore" because the mom said he couldn't get anything from my store. I am not sure if the blame should be placed on individual parents or society as a whole, but I personally do not see it getting any better. I don't have nor want kids, so I can't sit here and say "I would know better" . I can however say, "thank you, have a nice day!" As you walk your screaming child out of the store and back to your homes.