Americans are spoiled. Yes, we still weigh things in gallons instead of liters, use pounds instead of kilograms, and feet instead of meters.Even after more than ten years of having a dual labeling system -- which is a completely unnecessary expense and drag on innovation and productivity. eHow says "The meter has been adopted by virtually every major nation except the United States. The metric system is also used by scientists worldwide."
Oh, we could attribute this to the lobbyists who are pushing its continued use, or to the legislators who refuse to change it. But it comes down to polls and comfort. Polls, because most Americans don't want to change, they're too familiar with it, and legislators who have given up trying to change it.
We even teach the metric system in schools, along with "our" system of weights and measures. This is emblematic and demonstrates clearly a central fact of human nature. We don't like change. However, that's too bad. There comes a time when it becomes critical for survival. Okay, so use of the metric system doesn't seem like such a big thing.
Tell automobile manufacturing companies that in the U.S. Almost 8 million cars and trucks produced annually, yet only a small fraction are "American" i.e. 75% or more of the vehicle is made from American parts. Many American cars use nuts and bolts, for example, measured in inches. (I think) There was a time when this was true for all American vehicles. Those days are long gone. All foreign cars use metric sizes.