I drove the truck around a few days ago and saw four other trucks of the same make, year, and colour while I was out and about. So, I waved. And nobody waved back. I guess I spent too much time in my youth driving VW buses.
When I drove a '69 Volkswagen bus, everyone waved. Every other VW bus from any year, the driver waved, and I waved back. Sometimes even Vanagons waved! It got to be almost ridiculous, especially considering the sketchy transmission on that thing, which made it difficult to shift with two hands free, much less wave at someone. Usually, though, I let BAH drive, so I was free to wave.
On the motorcycle, most other motorcyclists wave, regardless of make of bike, except for helmetless riders. They're too cool, I guess. The motorcycle wave is a subdued wave, of course. You just lift a few fingers. Alternatively, you can put your hand down to the side and do a low wave.
School bus drivers wave to other school bus drivers. Sometimes, that would get to be too much for me to manage. I HAVE FIFTY KIDS ON THIS BUS AND I'M DRIVING! DO WE REALLY NEED TO WAVE RIGHT NOW?
The bicyclists who ride by our house a lot never acknowledge us at all, even when we stand right by the road! They're so in their own world. Usually they ride in packs and only pay attention to one another. They act like machines. If you are on a bike yourself, bicyclists who wear normal clothes will wave at you, and those in special bicycling clothes generally do not. A camel pack generally means you do not get waved at.
Any sedan I've owned or driven, regardless of make, was not wave worthy, except for the Mazda Miata. Other Miatas wave.
Why? Or why not? I have no idea.
Do you wave at anyone when you're out and about?