Right on red

The other day, I finally got around to looking up something that I've been wondering about for a while.  The fellow that I carpool with consistently turns right through a red arrow at a certain stoplight on our route, and I had always thought that this was illegal.  So I found copies of some relevant drivers manuals online, and discovered the reason for my consternation.

In Minnesota (where I learned how to drive), a red arrow means that right turns on red are prohibited.  You do not turn until the light turns green.

http://driving-tests.org/minnesota/minnesota-drivers-handbook-online/ , page 61: "A red arrow means “stop.”
You must come to a complete stop at the stopline, before the crosswalk, or before entering the intersection. When the arrow turns green, you may proceed in the direction it indicates."

In Massachusetts, on the other hand, where I currently do most of my driving and where the aforementioned stoplight is located, a red arrow is exactly the same as a red light-- a right turn on red is legal after you've come to a complete stop unless specifically prohibited by signage.  The arrow is basically only there for the opposite situation, when it's ok to turn (green arrow) but not go forward (steady red circle).

http://www.mass.gov/rmv/dmanual/chapter4.pdf, page 81: "A steady red arrow means the same as a steady red, circular signal (see the preceding Steady Red section)."