want to fix an american car–hope you have both metric and “standard” wrenches

I will point out that with the singular and shining exception of lugnuts, at least this one has not been the case since at least the 1970's. All fasteners on current(ish) American cars are metric nowadays and have been for quite some time. I've never seen a single one that isn't on any car that's not old enough to qualify for historic plates.

This used to piss off the oldheads to no end back when I managed a hardware store because they would absolutely insist, sometimes literally screaming in my face about it, that their dang old good old boy red blooded American Ford that they just bought didn't have no Jap pinko metric bolts in it anywhere not nohow, and 100% of the time they were wrong. (This annoyed me only slightly less than the people who showed up needing a bolt, didn't know what it was, didn't bring the old one with them, and the only information they had was "I took it off with a 9/16 wrench." Hombre, the head size tells me absolutely nothing about the diameter, thread pitch, or length. Then they would claim that it's just a "standard" bolt, as if there's any such thing. Also, a 9/16" wrench will usually fairly easily remove a bolt with a 14mm head, so that really tells me nothing. Or 5/8" on 16mm. Etc.)

Harleys, however, take it as some kind of point of pride that they actually do use fractional inch fasteners everywhere.

See also: the 9mm and 5 grams in my pockets

Although, to be fair, British people say that too, especially when Britain joined the EU. "You mean I have to stop measuring the produce I sell in pounds and ounces?!"

And, of course, they still use MPH. I imagine there would be a massive uproar if that got changed.

British have gone much further with metrification than the U.S. but there's still way too much resistance. And some of it is very silly indeed- weighing yourself in stone, which is a rather arbitrary 14 pounds.

Metric is undoubtedly an improvement, and if there were political will, I'd be all for a renewed push to make it the sole standard. Cultural inertia within a single large and wealthy country is pretty much the only "advantage" the older "system" has over metric.

I do get a little bit protective when people suggest that Imperial/Customary/whatever is nonsensical or useless, though. It's more that it's disjoint and obsolete. Units arise out of circumstances, and shit like using 12 inches to a foot makes a lot of division into fractions really easy. Same with 8 ounces to a cup, 16 to a pint, and so on. Dividing shit in half or thirds is a pretty easy paradigm to do math in your head if you're not really getting a lot of formal education. Most of the base units ultimately trace back to something perfectly sensible for a pre-industrial society.

So there's method to the madness, it's just that it was a thousand different methods, arising from various trades and merchants trying to standardize (yet also retain) their traditional measurements for their own needs. There's not the grand unified system that only really became workable with standardized manufacturing and improved communication in the 19th century.

The other funny thing is that while units can and do still cause confusion, many US Customary units are literally defined in terms of SI and have been for well over a hundred years. An inch, for example, is exactly 2.54 cm, because even in the 1890s Americans knew it was stupid to try match a metal stick in London to one in Washington to one in Paris with any greater precision than that, and only the SI had a set process to refine unit definitions in relationship to natural phenomena.

I did say that we hate learning. 😉

True! We used to use pounds, shillings, pence as our currency and I'm very glad I never needed to deal with that shit.

Doesn't need to be instant.

You can have a year or two where both metrics are given side to side on products, weather,...

Even road signs can just slowly update by hanging the new signs next to the old ones for a while, until the old ones are removed.

It is about disliking learning and the need to be contrary to the rest of the world.

It's corporations, really, that seem to insist on having their products and tools still defaulting to US customary units...

I am no corporate fan, but this one is not on them. They already sell the same products in metric everywhere else. If the US switched to metric, most corporations would be able to switch overnight.

I doubt the corporations care in any deep way, same as with anything else. It's just sort of a chicken and egg thing. They'll resist change as long as resisting is cost-effective, but that very resistance slows adoption. Still, they will likely shrug and adapt if it becomes obvious that people prefer metric, or even simply stop caring.

Did you go to school in the 70s or 80s? I don't think it's like that anymore.

Start with adding a few metric characteristics in imperial. A yard and a meter are pretty close, so call it a kilo yard and centi yard. Same for quart and liter. It's not switching to metric, but it's more logical.