Ok, now do one where C and A arrive at the same time to an empty roundabout and A still, to this day, thinks they have the right of way. Because why wait a fraction of a second when I can make others wait for a lot longer?
I hate having classes in a classroom with windows pointing to a roundabout because I get to realize how NO ONE seems to do them correctly... (In Spain, for reference)
Depends on the size of the roundabout. For one big enough they could both join simultaneously and maintain a safe distance, that's fine. If not, if you drive on the left the one on the right has priority and vice versa for the rest of the world.
In fact it's only a problem if people arrive simultaneously at all junctions, since now there's no person to the right of everyone.
In this case usually everyone stops (unless one of the cars is a BMW or audi) and then someone will start to move first. After which normal operational rules are restored.
A does have the right of way over C. And the OP has a quite violent interpretation of transit rules that only make sense if it's a large roundabout with a low speed.
Also, the pink car has the right of way over both. Both are quite right at stopping there, and D is invited to keep stressing themselves to death.
Now, if the pink car decided to stop and wait for A, then it maybe is worth pointing it to them.
I got my driver's license pretty recently and in driving classes I was always told to look at the left first to see if anyone is inside the roundabout, and then to the right to see if I have to let someone go before me (on small roundabouts). Think it from a logical standpoint: A wouldn't even need to completely stop to let C in first, while, if A goes first, C needs to stop and wait while A passes in front of them.
It may be a new rule, because no one seems to know about it (or pay it any mind).
Really? I thought you never look to the right in a roundabout. You look to the left, and if it's clear, you enter and look forward until you exit. That said, I've never been to a small enough roundabout that there could be a conflict just after entering.
The OP's idea here is that since A is stopped, C has plenty of time to enter the roudabout. That's reasonable if the roudabout is large, and crazy if it's not.
Your idea that C can enter anyway, even if A didn't stop is just crazy.