Be In Charge of Yourself

Why do people feel that they have to be in charge of everyone else and their actions? Why can't we just be considerate of each other?

I live in a pretty densely populated area of California. You have to be somewhat aggressive on the roads because there are so many other people out there. Yesterday, I had to change lanes to change to another freeway on my morning commute. Fortunately, since I take Sugarplum to daycare, I get to take advantage of the carpool lane (on the other side of the freeway)
So I'm merging over.. watching the lane next to me.. with my turn signal on and manage to do this successfully through 4 lanes without a hitch. It comes time to move over to my last lane and (with my turn signal still on) I calmly wait for the dude who is in a hurry behind and to the right of me to get in front of me. Then I take my place behind him. In front of another car.
I guess I didn't get the appropriate approval first though because the lady I got in front of decided I cut her off and started screaming at me and putting on her high beams. Like blinding me is going to make me get out of her way. Sorry, it just makes me slow down because now my vision is compromised.
Then she changed lanes and pulled up right next to me and is screaming at me waving her fist in the air. I glanced at her.. rolled my eyes and looked straight ahead. So what does she do? Increases her speed gets in front of me and continues to wave her fist in the air.
In a moment of great calm and maturity, I flipped her off. Sugarplum was clueless to the whole thing.
But it left me thinking, why do people have to be so rude to one another? Why can't we have a little common courtesy so as to let someone change lanes? As though the 3 second delay she might have experienced from having one more car in front of her is going to ruin the entire day. I just don't get it sometimes.