Not overtaking on the right in the USA means you're stuck behind granny going 60 in a 75 zone. Here in Denver, 4 northbound lanes on I-25 coming into town:
Leftmost lane = cars going the speed limit or 5 mph more
Next left = fast cars passing the above guys on the right AND grannies going 10 mph below speed limit
Right middle lane = faster cars going 15 mph or more above speed limit and street racers, plus more grannies and people going the speed limit and somewhat faster trucks climbing the 5% grade out of the valley between Castle Rock and Centenial
Rightmost lane = REALLY fast cars and REALLY slow trucks and normal people and grannies planning to exit south of E/W 470
And, having driven in southern California, I'd say Chloë is about average.
But then, I've also been in China where painting 4 lanes on the road means the cars will drive 6 abreast.
Good morning, Chlomo.