For me, as a male, it's not about vanity but about fit. As someone who is short (161cm ~ 5.5') clothing size becomes a hassle. I can't buy pants with a perfect leg because they always make them longer. So I then have to get them resized to fit or I roll them up. Resizing makes that pair of pants more expensive. Rolling makes those pants inefficient as inevitably they will unroll.
Shirts are the same. If I get a "Chinese" large, it's more of a "Medium" on me. This means the arms don't fit nicely and are more often than not too tight. If I was a body builder I would be fine with that but... well... have you seen the pictures of me? 🤣 But a US "Large" is the equivalent of an "XXL" on me and I float in them.
This is why I prefer a standard measurement of CMs. But even this seems to not be correct. Going back to the tape. My previous tape measure read 77cm at the waist before it broke. I couldn't work out why if it was reading that, why was my 87cm pants not sliding off me. My new tape has me back at 87cm which explains it nicely.
This leads me back to my question. Why the hell aren't tape measures a standard? A cheap tape measure using a standard measurement should read the same as the most expensive tape measure.