This has noticeably changed in past years. More and more thinkpads, more and more dogfooding

I'm guessing this is because macOS pulls from FreeBSD on a semi-regular basis.

Maybe they pull some things sometimes but I get the sense their command-line tools in general are just unmaintained and collecting dust. Do you have a citation that they pull regularly?

FWIW:

~ man rm | tail -n1

BSD January 28, 1999 BSD

They pulled at least once, historically, but don't seem to pull on a regular basis. Anyone who wants newer tools than the few they keep updated installs homebrew.