Giving a cyclist a leeway when passing from behind should be a requirement of the laws of every state. When they do that I don’t wave. I don’t want them to hit me anymore than I believe they want to actually hit me. When I get buzzed I might yell but it’s just a surprise reaction on my part. When drivers pass you they’re not looking back so the wave or giving them the finger for buzzing and all is really pointless IMO. Here in southern Delaware everyone waves including cyclists, pedestrians and other drivers but generally as a result of making eye contact by coming at you from the opposite direction not from passing you from behind. In NJ no one waved especially other cyclists.