Some things are sold according to metric measurements in the US. For example, Coke is often sold in 2-liter bottles. On most containers, metric measurements are given in parentheses. But when an American reads that 1 simple pound is 453.6 grams (approximately), he decides that the metric system is just too complicated to bother learning.
On the other hand, when I was working in Germany, a collegaue needed to know much two yards is. I explained that two yards is six feet, and one foot is 30.48 cm, and he told me he needed to know *exactly*, without my making a bunch of crude approximations. I tried to explain a yard is *exactly* three feet and that a foot is *exactly* 12 inches, and that an inch is 2.54 cm; he didn't believe me. It took me a while to convince him that one can indeed make exact measurements in the US, even if almost nothing is based on powers of ten.
(My other favorite is the statement by a German friend that American recipes do not turn out reproducibly because we measure volumes and not weights, and you never know how moist your flour is, etc. He showed me the German way of doing things, which is to take a measuring cup with different markings for flour, sugar, etc. I never convinced him that these are also volumetric measurements; he insisted that they were weights, and inherently more precise.)