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.

! There is right-hand priority in France! The absence of “Yield” sign means you must let the car from the right go, if they don’t have their own sign, EVEN if they’re from a smaller road (apart from private roads).

You were probably victim of a French person using their priority correctly, which is very misleading because you would have been found full-guilty. I call it an “implicit priority to the right” and municipalities use it abundantly to create slow traffic, but foreigners don’t always know that smaller innocent secondary streets can have priority OVER the main road of a village.

These signs are mostly on the highway