> it’s more common to see football pitches for large areas, for example That's the entire point of my comment. Everyone "knows" what 12 tonnes, 12Mg, 12,000 kg

> it’s more common to see football pitches for large areas, for example That's the entire point of my comment. Everyone "knows" what 12 tonnes, 12Mg, 12,000 kg are but they are internally recalculating to something they actually know. The Imperial system basically emerged from how people actually perceive things which is why every conversion is wonky. For instance, a bushel is about how many apples someone can carry, a cord of wood was originally an amount of wood bundled with a cord which has since changed definition, some for pecks, fathoms, and knots. If this still isn't convincing, consider that mach is basically the go to unit when talking about aeroplane speeds because thinking in multiples of speed of sound is internally what many would instinctively do anyway.