My impression has always been that the rules of right away on a rotary have been poorly understood in the US. For example I think that many people think that right away on a rotary belongs to the person in the rotary, except for Mass. I just Googled it, and yep there are blog posts were people as saying about the same thing (sometimes to inc. RI). I don't understand how this misunderstanding started.

The only thing that appears to be a little bit ambiguous per law is in NJ.
The New Jersey Driver's Manual recommends that, in the absence of flow control signs, traffic yields based on "historically established traffic flow patterns",[8] and there are no set rules.[9]
https://en.wikipedia.org/wiki/Traffic_circle 
I do not have any experience with this in NJ. The ONLY time we are in NJ is when we are on the toll road trying our best to exit the state on our way through it.

I believe that in the US there are/or were different rules about coming to a
Stop vs a
Yield when entering a rotary, but that is about it. (Oh, and everyone seems calls them something different).
