Replies to 'Coping with Stress'

I need someone to explain this to me. 

I am having a hard time understanding people.  From my point of view, I always give people benefit of the doubt until the other person proves me wrong.  I always give people ( in general) just an once of respect at our first meeting.  I always say thank you, sorry and excuse me.  But I feel like am the only one.  There is the saying that goes around in here, you teach people how to treat you.  Well....what is wrong with this way?  And believe me I am not a door mat either.  I have people who do not like me, because I am too direct. 

I can be walking along at the store, no one knows me, I have not said anything, just shopping and people will run into me, they step in front of me with out a word of excuse me.  I am going down the street in my car, I always run with my lights on, even in the daytime, people pull out in front of me, causing me to have to step hard on the brakes.   

Where did all these rude people come from?  Why is being nasty first always better?  Why can't people look beyond their own nose to realise there are other people around them?