It's also worth noting the French-English angle here. The meter was basically the Parisian yard; the crazy definition of 1/10,000th the length of a quarter-cir

It's also worth noting the French-English angle here. The meter was basically the Parisian yard; the crazy definition of 1/10,000th the length of a quarter-circle running from the north pole to the equator through France was picked because (a) it gave something very close to the Parisian yard and (b) it gave an agreed upon standard for all of the hundreds of disjoint local variants of the yard, as you mention. So now that everyone has already adopted the meter, it's the standard, but if you're back in 18th-19th century England, which already had a well-standardized national system of measure, and here comes your long-time rival France with a new standard system of measure, derived from first principles, they say, perfectly rational, and it just coincidentally is the same as their old unit of measure, you're going to be a bit skeptical that you should abandon your units in favor of theirs.