Why do we have have turn signals????????

Is it just me, or do you get frustrated with drivers that either change lanes without signaling or are just plain oblivious to the rest of the world?  

For an example, I was stopped at a stoplight turning right.  Here comes a car toward me in the right lane.  Traffic behind them a bit after a gap.  I could have shot the gap, but that would have been a little reckless.  So I figured I would wait until the car passed me.  

 I am sitting there, waiting, my turn as the traffic behind them is closing ground.  They begin to slow down......and I am thinking, "Are you turning, are you just slowing down.....what are you doing????"  Then they start to coast.  Ok,  No big deal. 

 Then they slow down even more, now the rear traffic is right on top of them.  About 25 cars.  Then, without signal, they turn.  Now I am frustrated.  Not because I am in a hurry, but because of the principle of the act.  If you knew you were going to turn, WHY must you waste my time waiting on you? 

 How hard would it have been to just signal and be respectful of others.....not just me, but the cars behind you, maybe the guy that was trying to cross the street?  I look at my communication with my borrowers, Realtors, title company and everyone else involved in my business, in the same light!  The process HAS too be the same principle.....to think about others and their time. 

There are so many other components during a transaction, and they have to know what direction I am going! I need to tell them what is happening, not letting them sit and wait. Sometimes the phone feels like it weighs 500lbs when having to disclose uncomfortable news. 

 But no matter what.........I have to always use my signals!!!!!  So everyone knows what direction I am going