they didn’t really try. it’s more of a suggestion (and still is). metric is standard in the US within science, just not among regular folks because commercially it’s not as dramatic, i.e. news stations dramatize 100F!!! since it sounds way more dramatic than 38°C. if the news and commercial products started using metric, people would quickly switch over.

unfortunately a lot of imperial shit has started migrating to europe due to chinese products being produced for the US market and then sold in europe as an afterthought using imperial units.