The English system of measurement originated with a human scale of reference. If it is in common use today (absent the no longer used Rods, Furlongs, etc.), most people have a good idea of what you are referring to. This is not the case with Metrics.
It works well for scientific calculations, but lacks some handiness for everyday human use. An example is temperature. The large divisions in Celsius are not as useful as Fahrenheit for air or body temperature. Air pressure (psi in your tires, etc) is another area where metric falls short of useful divisions.
Force measurements are another problem. I have torque wrenches with different metric scales, due to metric re-inventing of references. They have even changed the dimensions of the meter at least once since the system was started.
There have been some spectacular failures associated with measurements in Metric. Airplanes not fueled correctly, Spacecraft lost, etc.
Generally, the only items manufactured here in the US with metric dimensions are those intended for sale where laws mandate that(the EU). Or those that combine imported and domestic parts, such as vehicles. Of course, exemptions are made for items they need, such as high tech equipment
Will