Going metric inch by inch

As long as I've been in Canada, the metric system has been used. Gas is in litres, beer bottles are marked in millilitres. Speed limits are in kilometres. So, pray tell, why are crutches marked in feet and inches? Considering that I'm 5ft 7, my son now lokls down on me from his lofty height of 6ft 3. Oh, and by the way. I suspect that the crutches are made in the US. Strikes me as a shame that Canada, a first world country, can't support it's own crutch making factory ;-))

Ah well. Until tomorrow....