Weighing for side to side weights

Talking to a CAT scale repair man, he said the scales are platform scales and are designed to have a amount of weight across the platform of the scale. When only one side has weight it will read incorrectly. As it did in my test. He said why do you think we invest the costs of poles or curbs at our scales? to keep the dummys from driving off center and getting a wrong scale reading number. Makes sense.

This comes under old wives tales or CAT scale operators/repair sales or repair people, and isn't true at all for all modern single platform scales.

The CAT scale near me says the poles are their to prevent drivers from crossing the scales at at angles as they maneuver around the parking lot.

My certified for commercial use small town grain elevator scales has no poles on the sides. I can get any weight combo I need and they all add up to w/i 40-60 lbs.
Same with my companies loading yard platform scale where we could get our combo or truck or trailers gross or one side axle or one set of axle weights.

I've read on rv forums how a trailer had one wheel several hundred lbs different than the one in front or behind it. I asked my DOT guy who carries portables how this could happen. His comment was that it could have been a bad reading or a multi axle trailers side links may have got flipped at the equalizer bars or the truck or trailers brakes were locked up with the tow vehicles auto tranny still in drive or reverse. Good scale reading comes from tranny in neutral with no brakes applied.