It appears that people are simply too wrapped up in themselves to bother with good manners. When holding a door open for someone and even when I'm in the checkout and they ASK me if they can use my store card to get a discount on their grocery bill, I get no thank yous more often than I'd expect.
Every so often, traffic is like a life and death battle at times where people feel safe in their vehicle/cocoon to do as they please. Sometimes I actually pray to see cops pull them over or see them stuck on the side of the road, sidelined with some costly car trouble. That actually happened once. And yes, it brightened my day to see there is such a thing as karma.