If you go to the mall or the local mega-store, people are oblivious. They stop in the middle of the aisle and contemplate the situation while the rest of the people in the aisle try to find their way around them. People have no idea that they are not the only person in the universe. I've had people turn and yell at me because I had the nerve to say 'Excuse me' and try to get past them. Many people have no social conscience and do not recognize manners in others.
Many times displaying social graces is taken as a sign of weakness.
If you think so little of your own importance to be polite to others, I don't think you're important enough for me to be polite to. If you see the manners of others as a weakness and do not appreciate the courtesy of others, you will not see any benefit in acting courteously toward others. Our offices share the restrooms, and she and I seem to be on the same schedule. She does wash her hands, but then dries them, opens the door to leave with the paper towel, not her hand touching the door handle, then throws the paper towel on the floor. I've also come upon the woman at the sink repairing her makeup, and the wipes she uses she also throws on the floor.