FWIW, it’s going away with the newer generation, but anyone in France over the age of 40-50 from an upper middle/higher class education would likely follow similar etiquette. Not sure if it’s still the case, but French students were required to use fountain pens from 1st grade till at least high school when i was growing up (as a leftie, being schooled by old school teachers who made you redo any assignment that had smeared ink was painful).
Our son was still required to write with a fountain pen and was graded on penmanship. He was in the French education system to CM2 until we moved to the US 3 years ago.