That, and awk programs are almost perfectly portable across awk implementations: nawk, gawk, mawk (can't vouch for busybox-awk as I haven't tested it, though I've heard it's good as well).

This is of practical importance for portable scripts, since Debian uses mawk [1], RH ships gawk, and Mac OS uses nawk.

[1] mawk has recently received new commits by its original author after a hiatus of 20 years or so; see https://github.com/mikebrennan000