Youngsters might still be using imperial measures for their weight and height, but are only taught metric units at school. They are taught how to convert at about year 10, but by then the irks that don’t want to learn are so far behind the curve that conversions are probably like a foreign language to them.
It is often just passed on from their (poorly?) educated parents and journalists who refuse to metricate. Many youngsters have no idea how many pounds in a stone or inches in a foot. Possibly down to weighing scales that are really old and only have imperial units in large letters. Tape measure manufacturers are also to blame – there are still tapes with imperial measures on the top edge, with metric placed awkwardly below.
Students buy expensive calculators to convert, if they have to. Or just ask google or siri. A fair proportion cannot convert from the 12 hour clock to the 24h one. Even Joe Public have to change the clocks, twice a year, at 01:00h (or 1 am) to avoid errors, although that at least means the time change is completed on one single day!
In model engineering, the scales are so much more simple to use when down-sizing the imperial measurements from the original imperial items. Metric does not so easily lend itself to 12:1 scale conversions as 10 only has useful scaling factors of 2 and 5 and 10. But I know which is the easier for metric measurements of either a 10th or a 12th scale model!
Kit suppliers, like Hemingway, still provide the original plans in imperial units (but egine capacities are often metric). It will work its way out of the system eventually, but it may take a long time yet – what with market traders still often working in pounds weight!
At least most SI units make sense in that calculations of derived units are all standardised and most are decimalised.
Ask the average student to manually add up cwts quarters, stones, pounds and ounces and see how they get on! Roll on metric road signs! Who uses density of ponds per cubic foot on here?
I know a lot of the conversions but still generally use metric units ( even though I have to remember that 40 thous cut is about 1mm until I put a dro on my old imperial lathe. Miles per gallon is my one weakness – but once we change to kilometres, mpg will be put aside with no problems.