It is an accessibility layer for SI units. When I go into a bar in Australia and order a beer it is whatever the locals call it. A pot, a schooner, a pint. In

It is an accessibility layer for SI units. When I go into a bar in Australia and order a beer it is whatever the locals call it. A pot, a schooner, a pint. In most states a pint is 570ml which is about a 20 fl oz UK pint. Except in one where it is a bit less than a 16 fl oz US pint at 425ml so you have to ask for a real pint. It doesn't really matter because beer isn't traded across borders in pints. For science and commerce you can't afford the confusion over all these local units. But for ordering beer it doesn't matter. No issue with US sports using customary units. I use them all the time for height and sports in a country that has been metric for decades. But when science commentators or NASA use them I cringe hard.