I admit to being a guy who still thinks in feet and inches and then roughly multiplies by 3 something in order to discuss results with the metric-minded. Being an ex-oil guy, I point out that oil companies have little choice. Drill pipe in the U.S. is marketed in feet. Here in St. Pete we do our coring with an NX wireline coring device that uses '5-ft' lengths of drill pipe and casing. However, if you think it is the oil companies holding us back, here is a shocker.
Students learn engineering in feet, inches, and thousands of an inch.
So if you want to single out a group that is retarding our migration toward the metric system, blame the engineers. I wanted to blame lawyers but didn't know how. Lawyers are flexible and will give the client any number needed.