You're right. I didn't consider this too. Have you tried a language with units?
I've tried it in F# and seen it in Frink. I found it cool but havent found a need for it. I suspect that is at least partially due to being used to not having it in a language.
A friend of mine hacked up his Lisp, with lots of macros, of course, to check units at compile time. I haven't really used his system, but he was quite keen on it.
Yep, someone here added a type check to Ruby, there are some functions through the codebase that check each argument but I've not seen any real life benefit.
I've tried it in F# and seen it in Frink. I found it cool but havent found a need for it. I suspect that is at least partially due to being used to not having it in a language.