Not My Fault!!!

For the system to work, both switches (chassis switch and controller switch) must be in the same mode (A or B). In my experience, mode A is better, because the train starts and stops gradually, and in mode B instantly. So mode A appears to me to be much better and more realistic than mode B. 
 
I'm not sure why there are two modes at all, though. Could it be, maybe, in case someone uses two controllers?