@freemo , the USA has a weird hybrid system, where officially everything has to be done metric, but then translated to imperial for public consumption.
@Pat NASA. Auto makers use metric. Pharmacies use metric. Science is all metric.
@Pat , your car speedo is made with parts that use the metric system. 10mm nuts, not 3/8ths. Your brakes are held on by a 17mm bolt. The legislation that defines how the car has to perform in a crash is written in metric tons of force.
@Pat there are literally government regulations on this. Often so we don't crash another hundred million dollar probe onto Mars. https://www.latimes.com/archives/la-xpm-1999-oct-01-mn-17288-story.html
...or make a big space telescope that's out of focus. 😂
@Pat , slightly different story with Hubble, that was a part of the surface grinder that was put in upside down... but ya. Mistakes like that are compounded by having to convert units.
@JonKramer
My car speedometer uses mph. I've heard NASA refer to "Nautical miles". I don't think "everything" has be done metric. Science and medicine use metric anyway. I think beverage sellers are required to have liters on their products, and all food products need to have nutritional stuff on the package which is in metric, but I don't know which dept. requires that (maybe the dept of agriculture).