It's on the way out, but in Ireland people are colloquially weighed in stones, sheep in kgs and feed in lbs. For a while, speed and distance weren't compatible.

Metric money was a similar issue in the 60s. People still thought in shillings for decades. I read that historically (especially in Britain) entirely different counting systems were used simultaneously. Shepherds had their sheep counting numbers, sailors had a different one.

Dialects ran deep, not long ago.

Incidentally, it's lucky that metric never became known as "The French System."