I think part of the reason is that it's just a small minority that intends to turn right. For them, waiting is somewhat useless, as they're not crossing any oth

I think part of the reason is that it's just a small minority that intends to turn right. For them, waiting is somewhat useless, as they're not crossing any other traffic. Once the traffic light turns green, not many of those waiting turn right; most of them cross the road.