Yeah, numbers get you fun stuff like overflows and wrap-arounds, etc. But sorting is faster (sorting "99" before "100" is more complex than 99 before 100) and space requirement is lower (6 bytes can store a unique ID for 281 trillion objects, but 6 characters only permits 1 million if you're storing them as strings).

Or is there some datatype that combines the space- and sort-efficiency of a numeric type, but doesn't bring the baggage of assuming they represent quantities?