Division no is the problem in one unit, inch, feet, etc, because use fraccions instead of decimls, but the problem is the conversion from inch, feet to others (yards, miles), which is the source of a lot of errors, like those from the Mars probes or some catastrophigs breaks of bridges in the past, apart of some problems in physics, because using for weught and mass the same unit. No, imperial are not human measures, never has been since humans count with 10 fingers.