I think a bit of it has to do with the manufacturing sector. The 'industrial revolution' in it's beginnings was quite crude really. Today's space age technology was essentially led by America, and that in and of itself, I believe to be the contributing factor in our adherence to an essentially non-metric system.
Take the term TITS for ex.: Total instrument tolerance supplement. Even though the tech industry is primarily metric, the term itself alludes to getting the absolute maximum precision from whatever you are using to measure with regardless of the scale.