It turns out the metric system has completely won, but some just haven't realised it yet! If you are in the US, and need a definitive ruling on distance, weight etc then you'd think that somewhere there is the golden definition of an inch, a gallon, a pound and so on. There is. They are defined in terms of the metric system.

To quote at 8m45s in:

The most ridiculous thing about all of this? Every single one of these imperial measurements are legally defined by the metric system. America is already using the metric system, and most of the population is oblivious to is.

The imperial system wasn't even sensible. The US uses feet, but also uses surveying feet which are finally becoming one. US and UK gallons remain gratuitously different, so miles per gallons don't translate.

The final frontier are recipes randomly switching amongst volumes and weights with imperial units (quick: what is the weight difference between a fluid ounce and an ounce of water or butter?)