I have a good idea, lets all pick on the English and their stones (smile)
Yes, English stones are completely incomprehensible.
Anyway, I was taught both systems comprehensively, the inches, miles ounces thing and afterwards the metric system and hands down, no contest, metric is so utterly easy and simple. Even me, math dunce, can do the computations in my head if need be. Feet to miles and so on I couldn't even do on paper anymore, not if my life depended on it I fear.
And bodies similar? Wow, I am 1.77m and there are friends I have to look up to to talk to their faces and others whom I can kiss the top of their heads without having to face down.
And hands! Some are like spiders, so long and spindly - pianists by genetics you'd think, others so stubby and short. The same goes for the length of their strides. Some I can't keep up with because they are so tall and hence have long strides.
And let's not get started over the need for fractions: 1/2, 1/4, 1/8 of an inch and how to add things like 3/8 and 1/2 and 17/32 of inches? How utterly complicated.