You're probably right to feel that way, but perhaps you can lower your blood pressure by thinking, 'they're too busy paying attention to the road than to wave at me'.
Again, not that you're wrong, but sometimes when you're the grown up, you're not recognized for being one.
Whether I'm in a traffic lane or in the bike lane, if someone comes to a driveway or side street and stops, or at an intersection stops and does not make that possible left turn in front of my path of travel, I give them a wave of acknowledgement. As a motorcyclist as well, I have subscribed to the 'show them you're a human' school of thought and possibly they get a small bump from my acknowledging their noticing me.
It may not work that way, but I like to put myself in that frame of mind, fwiw.
Leo H.
Sun Valley, NV