SAE tools for SAE hardware. I agree, saying something like "gimme a 7/16 wrench for this 1/4-20 by 3/8 bolt" is probably like speaking a foreign language to someone accustomed to metric. But you get used to it if you see it every day.

Now metric measurements of wire are fucking ridiculous in my eye. AWG (American wire gauge) all day. The metric equivalent measures the diameter of the wire and calls it like 1 mm2 for 18 awg, 1.5 for 16, 2.5 for 14, 4 for 12 awg etc. AWG keeps it nice and easy, every other even number starting at like 32 down to 2.

It does get a little fucky from there tho lol. Like then it goes 1 and 0 AWG, then 1/0, 2/0, 3/0, 4/0 (pronounced like 1 awwt), then 250, 500, 750, 1000 MCM. But I've also heard those sizes of 250-1000 called KCMIL instead for.... reasons....

It's like most of our measurements. It's what "feels" right if that makes any sense. Fahrenheit is more accurate to what changes are noticeable to the human body, a foot or a yard just paints a way better picture than half a meter etc. I'm sure most of it is based off like farmers or something rather than scientific measurements.