You can't makes broad, sweeping generalizations like "UK/US type self checkout." It varies so much. I live in the US and the only place I ever go to where they

You can't makes broad, sweeping generalizations like "UK/US type self checkout." It varies so much. I live in the US and the only place I ever go to where they weigh the items you scanned is Costco. Everywhere else I go (my local Walmart, Target, Aldi, two local grocery stores, and CVS) the self checkout is mostly based on trust with maybe one employee somewhat monitoring some machines. No random sampling. The only issue I ever run into with the self checkouts is double scanning the product. You do need employee to void items.