I really think the resistance to switching is political. America does a lot of things differently than the rest of the world, and the people in power want it to stay that way.<p>They see some advantages to keeping the general populace on the imperial measurement system.<p>1. They are afraid of problems which might surface during a conversion from imperial to metric due to the large population.<p>2. They want to make it harder for the populace to compare things in the US to the rest of the world.<p>3. They are lobbied to keep a non-decimal measurement system in place to make it harder for customers to compare product sizes vs. price.