Your average person doesn't think, realize, or know that they are an asshole. And, all the while you are thinking that they are doing all this shit on purpose to make your life hell, they are oblivious. Also, in their mind, you are already probably an asshole for something you don't even realize that you did.
So, confronting them on their asshole'ness only confirms to them that you are an asshole and gives them the license to key your car and rip up your mail.
Give people a reason to try and accommodate you. Don't give them a reason to smear shit on your car. Approach them with some kindness, humility, and patience. Calmly explain the situation and what you hope could change. Proverbs 15:1 "A soft answer turns away wrath, but a harsh word stirs up anger."
Yes, you have to decide to be the bigger person in these situations and that isn't fun, but in the end your life will be better.