I’ve noticed that people give the courtesy wave less and less when driving. I don’t mind letting people in when there’s traffic and they can’t seem to find a break in the cars, but show a little respect for the kind person allowing you in. A little rise of the hand is all you have to do. I’m not saying get out of your car at the next red light and thank the person for letting you in, just wave. It’s not even a wave, it’s a lift. It takes a second and the person letting you in will feel like they’ve actually done something today.
On a separate note, people who are trying to get out of a parking lot or space may be given a wide opening to get onto street, but they might not be paying attention because they are texting or talking on the phone. People like this need to pay attention. You probably have this nice person letting you in, but you don’t know because you’re “busy”. Here’s a thought: put all matters aside when entering traffic. You don’t want to leave someone stopped for an extended amount of time while you’re talking to you’re girlfriend/boyfriend about how much you love potato salad.