I know that no one can really answer this, but it gets to me sometimes.
I was leaving the supermarket today, pushing a large trolley full of shopping. It wasn't busy so plenty of space to move around. A woman walked into the back of me and kicked me, then instead of apologising she barged past tutting and calling me names.
Another example, I stop at a Zebra crossing to let waiting people cross the road. Car behind me starts beeping like crazy.