Its quite possible that educators are the only comprehensive users of Systems International(e) units.
UK was supposed to have gone Metric in 1971, but in the 21st century whenever I'm in UK I still have to mentally convert to driving in miles per hour and buying things by the pound. Money was of course, successfully decimalised - much to the chagrin of Mrs B who had to learn LSD (pounds, shillings and pence - remember those?) at school in Malaysia, even though the local currency was Straits Dollars and Cents. I remember once asking for twelve feet of dowelling in a hardware shop. I was told scornfully that it was "measured in millimeters now" but when I came to pay for it, the price was thre'pence a foot!
Like most people I've learned to mentally approximate pretty well; when in England, doing a hundred 'Klicks' is about sixty m.p.h., half a kilo becomes 'a pound o' mince' and a litre of milk is - well b*gger me! - a litre of milk! Whatever happened to the good old pinta?
But approximation is no good when you're committing engineering. Do the sums properly, on a slide rule, and hope you've got the conversions right.