leenia: scientists and accountants have computers which basically use the binary system, i.e. units of 2, 4, 8, 16 etc. Sometimes rounding is necessary, whichever subdivision is chosen.

It is generally advantageous to have subdivisions matching the number system used. All human beings, as opposed to computers, are now using a decimal system (arguably not the best possible choice). Therefore, whenever worldwide standardization is required, decimal subdivision has a head start.

Pocket calculators can easily convert between any existing unit systems. So it should not be difficult to answer questions like "which is more?" even if, say, one car manufacturer says miles per gallon and the other says litre per 1000 km. Laws can try to facilitate the calculations, but they cannot spare you thinking. Clever manufacturers or dealers have more advanced tricks to make their products look better than they are. -

"Illogicalities": salary paid per month rather than per working day.