Yeah, they’re both arbitrary. You agree with me.

The “things” being counted in either respect are abstract and are only “known” if they are familiar.

I’m not really following. What, are we counting feet, then? Mine?

Feet are just really entrenched in the way Americans think about lengths. It may not sound like it’s abstract, but it is. If I said “yeah, it’s about sixteen hands long”, people would have to parse wtf I’m talking about, but then have to grapple with how long a “hand” is exactly and what 16 of them means.

But you don’t measure the number of scooters by the gram either.