This really could not be further from the truth. US mechanical engineers design in ANSI units of measurements. If you go into a engineering lab in the US you find 4-40 you don't find m3. Certain industries are almost exclusively ANSI units. Aerospace for example, a majority of systems are in ANSI units. Boeing, Collins, Honeywell, Raytheon, Lockheed, etc, etc, etc all ANSI. Airbus who integrates many of these systems takes them in ANSI. The joke is there's two type of units in engineering, the ones that have sent people to the moon and everyone else.