Interesting, I've driven in 15 different European countries and found France to be one of the easiest and most chill. I mean, on the highways and city streets, anyways -- not so much on the farmland single-lane roads that shockingly have a speed limit of 90km/h lol ... but regardless, the "people merging in from the right have the right-of-way" actually makes sense to me since they're engaging in the most "high-pressure" action, while those of us strolling along on the highway can just adjust our speed to give them space, or change lanes ahead of time as needed.

Reduced to 80km/h since 2018.

I don't think they're talking about merging on a highway?

Sounds like they're talking about the fact that at an intersection, unless signaled otherwise, the people coming from the right have right of way.