I think the metric system facilitates trade, especially in bulk quantities of raw commodities, between different industries and jurisdictions. And, I think the

I think the metric system facilitates trade, especially in bulk quantities of raw commodities, between different industries and jurisdictions. And, I think the decisions made to arrive at a universal standard are a combination of top down and "perfect" that typify nineteenth century science. Earth doesn't have a 40,000km circumference, but it doesn't matter because anyone who needs a precise measurement will use some sort of aid. Similarly the mass of water in 1 mm of rain over a hectare isn't actually 10,000kg, but you'll use some aid if you need a more precise number taking temperature and actual contents of rainwater into account. Of course using nautical miles or acre-feet with high precision required aids of some kind, too. However, legacy systems of measurements were developed to minimize the number of instances where people like machinists on a factory floor need an aid such as pen and paper to do a calculation. Big problems like Fermi estimates are much easier with the metric system, but day to day problems within a specialized profession probably are not. I do think the benefits of a more universal system vastly outweigh the costs to convenience for everyday users of measurements, but I am skeptical of many of the rationales used for advocacy. Perhaps if an international system of measurements was designed today it would be even better designed for binary computers as computational aids rather than decimals and paper, though that would be an even more difficult transition.