> Woah woah woah, don't put that evil on us in the USA, that stone madness is all British.

> A US hundredweight is 100 lbs.

The fact that there are more than one sort of imperial measurements, and that they are different, makes matters worse, rather than better. The metric system works the same, everywhere, in all countries, and in all languages. The only thing that changed since its inception, was switching from defining base units through comparison to physical templates, to defining them by natural universal constants, aka. making it even better than it already was.

> The metric system didn't invent water volume and weight correspondence

I didn't say it did, I said they depend on one another. And in metric, that works for ALL weights and measurements, and does so consistently. Cool, so 1 pint of water == 1 pound. How much is a pint in cubic inches? How many cubic furlongs of water do I need for 10 imperial Tons?

Oh, and btw.: What exactly do you mean when you say "pint"? Because there are many different ones. Just a short list of examples:

    - Imperial Pint (568ml)
    - Liquid Pint (473ml)
    - Dry Pint (551ml)
    - Indian Pint (330ml)
    - The Australian pint (570ml)
    - The South Australian pint (425ml)

Source: https://en.wikipedia.org/wiki/Pint#Other_pints

If I have to rely on context, locality and customs to have a chance to understand what a unit of volume actually means, then there may be some issues with the underlying system. One reason why the metric system was invented, and why today almost every country in the world officially uses it, was to solve exactly these problems of ambiguity.

When I say "liter", there is no ambiguity, it's always 1 cubic decimeter.

> The motivation being global compatibility, not internal consistency.

All the more reason to officially switch to metric. Because as of right now, only 3 countries in the world (US, Liberia and Myanmar) officially use imperial units, while the rest of the world uses the metric system.

> The US was an original signatory of the treaty of the Meter.

So? If I have a gymcard and don't go to the gym, it's not doing me any good.

> It's nice to have but really reads like marketing wank. What matters to people doing work is if they can do their jobs.

Indeed it does. That's why science and engineering are using the metric system. Including NASA btw. Being able to convert measurements easily, and have them correlate with our most common, radix 10, numerical system, is not "marketing wank", it's a built-in advantage.

If I want to figure out what mass of water falls on an area in the metric system, I can do the calculation in my head. If I have to figure out hundredweights per acre, given that X inches of rain fell, I'm gonna need a calculator, a conversion table, and social context to know which kind of "hundredweight" I'm supposed to use.

Oh btw. people "do work" in all these other countries. And guess how they measure things when doing that? Exactly: In meters and kilograms.

Machinists have no problem working with designs in SI units on an inch-based machine. Lots of American companies use metric in designs and machine shops have to deal with it, although shops are moving to metric more and more. When they do this they keep and use their old machines with no problem although it’s an annoyance. Conversely metric machine shops can make inch-sized parts with no problems. Lots of material stock is inch-sized in the US, so even when you design in metric you have to consider this. But over time there is more metric stock available in the US, and for things like precision shafts there’s no cost difference anymore.

Regardless of everyday usage, in mechanical engineering/metalworking, the switch to metric has already been happening slowly since the 70s. Old machines and designs can stay in inches but most industries are already moving to metric unless there’s a compelling reason not to. You can see in Canada what things have stayed in inches because of regulations and material availability. House framing and steel weldments come to mind.