Why must people be rude?
How can they have so much disregard towards others?
Why is that person so self centered?
Think of when you are seeing this passer-by that appears rude. Think of how you will never see them again. In that one moment in time, the stranger was upset or angry or perhaps in thought about something. Perhaps that person wasn't actually rude at all. Maybe they were just distracted.
You hear frequently about "maybe that person cut you off because they had an emergency" or "maybe the mother was late to pick up her child" or even "one last time being at work late could end my career". Recognize these statements. There are millions of combinations of reasoning. Please reflect on them.
It is very cliche to hear "everyone is fighting their own battles", but it is true. You have no idea what is going on in another person's life or the struggles of their day. Just because someone didn't say thank you when you held the door open for you doesn't make them a bad person.
People may need help. But sometimes you should really mind your own business. Forget about others and meditate upon yourself. YOU are who is important first and foremost.