Fractional math of a US tape measure is certainly more complicated than it needs to be. I’d rather just add and subtract directly than find the common denominator and subtract that in my head.

US car manufacturers got halfway through converting to metric, but decided to keep a few things that require SAE tools, cluttering up a garage or shop with slightly different tools.

Ounces vs fluid ounces is infuriating. So is having a recipe call for a pint of blueberries but blueberries are sold by the dry pint. Making larger or smaller portions in grams/weight is way easier than figuring out what sort of measuring spoon combinations you need for making a smaller/larger portion of a quart ingredient.

it's so complicated i definitely don't remember ounces in a pint or quart or yards in a mile, let alone any of the less common ones despite living in this shithole.

division by 10 is the easiest division you can have in base 10

yes, it's generally easier to remember 10 as the conversion number and nothing else, and it's also easier not to have to add/multiply fractions of an inch in your head.

this also works between types of units, so it's pretty simple to remember that 10cm^3 i'm a fucking idiot, it's a 10cm x 10cm x 10cm cube, so 1000cm^3 is 1l is ~1kg of water, for example.