People in 18th century France did not have the means to measure weight outside of Paris. There were no traditional measures for weight, and we have no real way to know the size of the volume measures that were in use, other than reports from both French and English sources that confusion over measurement led to endemic fraud and that it was difficult for individual farmers to take their own goods to market.

I need to do more research, but I am coming to think that the stone may be the traditional English measure of weight while the pound was invented by scientists so they could do their work. Customary measures derived from England may have survived better than the customary measures from other countries because those measures make a kind of system.

Which brings us to the idea of measures evolving. English measures don't make a sort of system because they evolved that way, but because government officials picked definitions, sometimes arbitrarily, and then backed up those decisions with actions. People in small town England knew about scales because government officials has them. (Measurement is a learned behavior.) Feet and yards and other measures varied from town to town, but that variation was limited by the existence of physical standards and the fact that once in a blue moon one could show up in your town and you could get in trouble if you were selling or buying using anything different.

(This post is heavily indebted to La Grande Metrication by Louis Jourdan. I also recommend The Measure of All Things by Ken Alder who makes the interesting point that many traditional measures are based on the amount of time it takes to do something.)