Imagine how many road users in France today still don't know it's importance. Vehicles coming out of these (often very minor) side roads from the right can just pull straight out onto the bigger, faster road (if they dare!), and they're well within their rights. Woe betide if you don't stop in time and rear-shunt them. Your fault. If someone is behind you and rear-shunts you while you brake/slow right down for checking a side junction, their fault! I've seen people driving at 80kmh past these little side roads without a care in the world!
Only in France?!!
