@His_Highness, agreed ^^^
Being nice should have limits on the road.
I wish we could all just have a better basic understanding of things like right-of-way, rules of the road, etc. and Fuck excessive courtesy (sometimes). I'm not saying there's no place for civility and courtesy, but those are already underlying assumptions when we're all trying to get somewhere.
Breaking from expected behavior in an effort to be courteous can be just plain dangerous, not to mention frustrating. If we all just followed the rules, we'd all be more predictable and safer drivers.
When I've lived in more rural situations, it's just waving to everyone all the time.
Not so much in the suburbs, where you may get a hairy eyeball or worse, get yourself put on a list somewhere!
But I almost always wave to a flag-person. Breaks their monotony and might help 'em stay alert. They're spending hours directing people, most of whom don't acknowledge them.