They are trying to charge you at that rate probably 1 hours labor rate. Some rv repair places that have scales do that. The scales are not cheap, approx $4500 each, so they could get by with 2, but if they have 4 or 6, it will take years to recoup their investment. A CAT drive on scale is depending on the ground work needed to install at the low end $60,000 and up to over 100 grand. The truck stops are not using the scale business as a sole means of income, otherwise they could never charge $10 and expect to make any money. Don't forget those CAT scales need repairs and service adding to the costs yearly. Contact RVSEF in Florida to see of they can help you.