The US uses the metric system in some places, but that is not to say it is "on the metric system"- after all, all road speed limit signs are still in miles per hour, as an example. Fuel is priced in dollars per gallon. Consumer goods are almost always sold in measurements of pounds, ounces or gallons. People are measured in feet, inches and pounds on their ID cards and at doctor's offices.

Metric has made almost no inroads at all in anyone's daily life here.

> There's no way to gradually switch from LHT to RHT, you have to somehow do a switchover in a day

You could do it in phases. Have the trucks switch over on Monday, buses on Tuesday ...

And the US and various other countries (like the UK) effectively use hybrid systems for units for many purposes. Science and engineering in the US are heavily metric.

I used to think about whether we can get more countries switching back to LHT, but with Autonomous Vehicles that will no longer be much of an issue in 10 - 20 years time.

You'd also have things like bus doors now being on the wrong side (traffic-side), road curvature being wrong (e.g. motorway junctions and entry/exit ramps), let alone car mirrors and driver positioning.

> It would be way more annoying for LHD countries to change to RHD

As a complete aside, 1 country has done this: Sweden on 3 September 1967 and "It was by far the largest logistical event in Sweden's history"

https://en.wikipedia.org/wiki/Dagen_H

Hong Kong drives on the left, mainland China on the right.

There are enough standards that don’t have non-metric alternatives like the square drive of socket wrenches or a lot of bicycle standards. It’s very unlikely that they will get replaced

Thank you for informing me that China is likely to take over all manufacturing when it comes to cars. I am appalled that there are no US, Japanese, South Korean, Indian, Vietnamese, Russian, or any other nations that manufacture cars.

It also sounds completely plausible that a binary choice like left hand or right hand driving can be switched in a way that drives a pressure campaign that nations will give into China on because it’s an easier short term choice and wouldn’t gain an immediate reaction to due to the enormous cost that would be rapidly felt.

The US drives on the right (which is the right) side. So why would the US switch? Its really just Australia, Japan, India and the UK that drive on the left. The other 190ish countries all drive on the right.

PS Your 240V electric grid works that way because when the US switched to 120V (in like 1900 or so), we sold all our old gear to you and you never switched. So now all your electric things cost more as a result and your electrical outlets will kill you. So your decision making on such things is suspect.

With imperial you have weird fractions instead of decimals. To know that 3/4“ is larger than 1/2“ I have to actively think, decimals come pretty naturally (which was probably different in times before people went to school and learned to do math on paper)

I feel like neither system is inherently better outside of familiarity and I don't care which is used I'm just tired of having to own two sets of tools.

American money is fully metric.