John, as I understand it, the "decimalisation" of feet and inches into 10ths was an American initiative in fine engineering work, particularly lathe and milling work, in the late 19th century and early 20th century.
The U.S. also adopted the "survey foot" which is a foot divided into tenths.
However, the American "yard" was redefined in 1959 to bring the U.S. into line with the yard used in the rest of the world - which left the "survey foot" as a different measure again!
Survey Foot versus International Foot: What?s the difference? | MicroStation Today
Maybe one day, the U.S. will actually go fully metric, despite the metric system being French!
I've been informed that all major U.S. manufacturers have been prepared for changeover to metrication since the late 1970's, and could change virtually overnight.