Unless `units` doesn't happen to be installed by default, which is the case at least for Arch Linux.

Though it doesn't contain `units` either, here's a Wikipedia list of the standardized (IEEE 1003.1-2008) unix commands. http://en.wikipedia.org/wiki/List_of_Unix_commands

units(1) was in V7, and systems that aren't a superset of V7 are objectively wrong.

Debian same here.