The American thousands of pounds thing is even more weird than that: I buy gravel from the gravel pit. They weigh my truck and dump trailer in lbs and then charge me per ton. Everyone talks about tons: e.g. I'd call a dump truck operator and ask him to deliver 18 tons of rock, not 36,000lbs. But the weighbridge and road signs and regulations about vehicle and axle weight are always in lbs. If you only read things and never talked to other people you'd never know tons existed.

A lot of the older "no vehicles over X" signage is denominated in tons.