If you want to know the reason, it is because basically, three or four cars get to go through a green light. When you have to get someplace, it really plays with your nerves when you must stop every six feet. This is not an excuse, but it is a reason.
Also, if the car can’t turn he will have to wait another half a minute till he can think of trying again, while a pedestrian only has to wait till that car turns. I rarely get stuck when walking because of turning cars, and I totally understand those who turn right in front of me. It is usually at most 4 cars. There is ample time to cross.