That is stupid-- since my guess is a lot of people don't stay in their lane making the right turn... I lived near an intersection like that, and most people treated it like a normal turn, and there were all sorts of near misses as cars changed lanes during the turn. The other thing that stinks is that if someone is holding up traffic waiting to make a left, I am sure it is very tempting for other drivers to use the outer right turn lane to drive straight ahead.
Of course the ultimate irony is that there a bike lane on the other side.