Turn Signals are not Always a Polite Request
Every now and again I end up scratching my head and wondering why I didn't think of it that way. This is one of those times and it has to do with turn signals. Ask most drivers what they mean and the response will probably be that a turn signal is a request to change direction or move from lane to lane. That isn't necessarily so.
In some circumstances a turn signal may be an indication from the driver that something beyond their control has happened and they will be moving because there is no other option. If you are the dominant driver and insist upon your right of way it may be the worst thing that you could do in the situation. Giving way could prevent a serious situation from becoming worse or avoid creating a new situation that could have a negative impact on you.
I was trained in the Smith System of driving. Two of the key concepts in this system are Aim High in Steering and Get the Big Picture. In other words, see, evaluate and act on distant information as well as avoid mistakes by having a complete awareness of what is going on around you.
The commercial vehicle driver I was discussing this with observed that it is rarely more important to live in the moment than when one is driving. If you have complete situational awareness because you are paying the required attention to the driving task you would realize that giving up your dominant position made good sense. Infringing on your right of way is not always a challenge to be met with an aggressive reaction.