No idea. In Europe you put weigh them in the veggie section, type the code in, put the sticker on your bag. In China, the same thing happens, except there is an attendant to do it for you.
The USA, this is always done at checkout. If it was a law making that happen, it would have to be at the state level.
The USA, this is always done at checkout. If it was a law making that happen, it would have to be at the state level.