Somewhat related, but I have the worst time trying to convert numbers in my head from long scale in Japan (used to be used in the UK as well) to how it's used in the current English speaking world. So basically they put four zeros per comma as opposed to three, and the names of the numbers reflect that. 1, 10, 100, 1000, and 10000 are all unique number names, but after that comes 10 ten thousands, 100 ten thousands, and then 1000 ten thousands before a new number name at 1,0000,0000 (or 100,000,000).

It wouldn't be so bad to just memorize that 100 thousand is "new number name" if that's all it was, but numbers like that in daily life are pretty much used to talk about money (or somewhat less commonly populations). So once I get the actual number I have to divide by about 100 (or 150, depending on the strength of the yen vs dollar) to think about what it actually means in units I'm used to, like seeing an article saying a government project costs 1.2 billion yen doesn't mean much until I think about it like 12 (or 8) million USD instead. So I can never really use big numbers in conversation without manually counting zeros in my head.

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

I wish we had a metric inch because the fuzziness can be useful.
"How small do you need these veggies diced?"
"2.5cm ish" vs. "about an inch"

I feel like the implied margin of error is much larger for inches, which make them useful for many things where precision isn't necessarily desirable (hemming, wargaming, moving furniture, etc..). If I'm wargaming having a limit on rounding is useful (half an inch - either round up or down), assuming I'm playing at a scale that uses inches.

Feet I have no use for, with one exception - adult human height between 5' 2" and 6' 2". There I find metric too precise (whereas to the nearest inch accounts for variance in sole thickness, hair volume, etc.).

I wasn't raised on imperial (and I'm baffled that people younger than me in the UK still talk about stones. Sixteen stone is fat, sure, but I've no idea how fat if not told in kilos) but I find inches to have their uses.

Also miles for cars - because common speeds are ~60 and ~30 mph so a road sign effectively gives the time to arrival (e.g. 13 miles on a motorway = about 13 minutes). I don't use them for actually measuring distance on a map but they're handy when driving.

Do we have meter cola?

Oh, get off your high horse

Your basic unit for speed is m/s, but for most day-to-day purposes you use km/hr. The conversion between the two isn't even an integer!

Not only that, but your system, by virtue of being decimal, inherits all the shortcomings of our quite flawed numbering system. You can't divide something by the second smallest prime number without breaking out repeating decimals.

In my opinion, a good measuring system would make up for those shortcomings instead. It should be divisible by at least the numbers you can count on one hand. Decimal covers 2 and 5, so ideally the measurement unit would cover 3 and 4. So that would be a base 12 system. Technically 4, being 2², would be covered too, so 3 would do just fine. Ta-da! 12 inches in a foot, 3 feet in a yard.

My ideal would be 21 though, get that 7 factor

If you like intervals of 1000, you'll be delighted (or mortified like me) to know that 7×11×13 is almost exactly 1000 (it's 1001)