Well, most other countries around the world think metrics (formally SI, "international system"). In this regard, USA is exception, not rule
Said that, here in Brazil we do both. Many people use the original books (in English) and learned to use feet, miles and pounds (most of time stopping to do mental conversions). People that use the translated versions use SI units, which are very more intuitive for us. The translation uses 5 ft. = 1.5 meters, which is very near anyway. And 1 lb = 0.5 kg, which is not very the mark, but does a good work most of time. But once we hit ounces, acres or gallons, well, chaos is assured.