In physical trades like carpentry, brewing, farming & so forth, being able to easily halve, double or treble quantities is quite convenient. The customary units, being based on powers of 2 (with a few 3s thrown in …) tend to be really good at this, as anyone who's ever brewed or handled produce in standard units knows.
Dealing with French units is a pain.
(as an aside, the reason I call them 'French units' is because the name 'metric' privileges them: our standard units are no less a system of measures than are they; this too is my problem with 'SI,' since our system is (or was) likewise international)
The dishwasher was intended as an example for carpentry: standard kitchen cupboards etc are made in multiples of 300mm. It's the same for things like floor tiles, doors, etc.
No farmer or brewer deals in units that are easier to half in American rather than metric units. They use tonnes, hundreds or thousands of litres, and large areas. Outside America, they don't need to convert between units of the same type: no acre-feet, bushels, pounds, tons, or all that crap.
Calling them "French units" sounds like xenophobia. The American system was never international, and the British system didn't extend that much further than the French, at the time of the empire.
> They use tonnes, hundreds or thousands of litres, and large areas. Outside America, they don't need to convert between units of the same type: no acre-feet, bushels, pounds, tons, or all that crap.
In America, anyone who would deal solely in tonnes can deal solely in tons; anyone who would deal solely in hectolitres can deal solely in barrels (traditionally, 128 quarts); anyone who would deal solely in kilolitres can deal solely in tuns (traditionally, 1,024 quarts). No-one in America has to say '7 tuns, 2 hogsheads, 3 gallons, six quarts and a fluid oz' any more than he'd say '7.2850546 kilolitres.'
> Calling them "French units" sounds like xenophobia.
Oh, I'm not xenophobic! I just don't think they deserve a privileged position.
> The American system was never international, and the British system didn't extend that much further than the French, at the time of the empire.
The American system was used in Liberia; prior to the Russian Revolution the majority of the peoples of the world used systems of measurement substantially similar to the Anglo-American system, and could (should have, IMHO) rationalised and standardised that, rather than adopting the objectively inferior decimal principal.
> anyone who would deal solely in tonnes can deal solely in tons
Then your argument that these quantities are easily divided is irrelevant.
> 7.2850546 kilolitres
My house's water meter measures up to 99,999.999m³, or in litres up to 99,999,999 litres.
Europe other than Britain and Ireland didn't use the British system, and neither did their colonies, China, Japan, etc. All the British colonies except the USA chose the metric system after independence.
The SI system is the only one that's truly international, set up by international treaty between many countries.
And really they are SI units, the 'International System of Units', which may or may not 'privilege' them, but is certainly both correct and normal usage.
Dealing with French units is a pain.
(as an aside, the reason I call them 'French units' is because the name 'metric' privileges them: our standard units are no less a system of measures than are they; this too is my problem with 'SI,' since our system is (or was) likewise international)