Are they cutting them off, though? If the street you're turning onto has two lanes, it shouldn't be a problem for two cars to turn at once. The car on the inside is required to turn into the nearest lane (according to any state law I know), so why can't the car on its left turn into its own lane?

> Are they cutting them off, though?

Its possible for multiple lanes to turn without anyone cutting anyone off, but its also possible for people to turn right from the middle lane of the source street into the rightmost lane of the target street, cutting off people in the rightmost lane of the source street attempting to turn, or to make a right turn from a middle lane that is not allowed to turn, cutting of a legal right-into-any-lane from the rightmost lane when it is the only turning lane, so if someone explicitly says that's what they see and there is no available counterevidence that they are misreporting their observation, questioning it accompanied by a description of how it is possible for people to turn from multiple lanes into distinct lanes in harmony without anyone being cutoff is not particularly useful.

> the car on the inside is required to turn into the nearest lane (according to any state law I know)

That's the base rule in most jurisdictions, but there are places where it doesn't apply. See, e.g., for California: https://law.justia.com/codes/california/code-veh/division-11...

You’re not allowed to double right turn unless it’s explicitly marked, at least in the US.

If the right lane goes straight, you can't turn right from any other lane.