Advice on right of way and flashing rules when changing the direction of the main road

A shocking number: In an Internet survey, the situation shown above on a main street changing direction was answered incorrectly by around a fifth of the participants. They gave way to the blue car. Not correct! The red car turns left, but comes off the main road.

So the red has the right of way – even if it is recommended, as always, that the red expects the blue to behave incorrectly. Apparently such turning main roads cause confusion after all. And there is almost no blinking here as it should be. Blick therefore mentions the rules to freshen up.