Stand on the scale first and confirm your weight is displaying on the scale! After running 10k+ pounds to the same place in the process of clearing out a building, over the course of 6 months, I noticed the scale glitching today. Stood on it and it showed 187 when I weight 209. Even confirmed my 209 on a smaller scale for cans. They reimbursed me for my lost weight today, but the money is irrelevant to me at this point.
Made a few phone calls, but regardless of the fines they may receive, there is no justice for those guys depending on scrap income to make ends meet.
If you see they're cheating the scales, just drive away without saying a word and call your cities Office of Weights and Measures.