It's late afternoon, the sun cuts low, highlighting many details in the trees that I admire while I drone up and down the hill on my mower. There's little humidity; the quality of light is already shifting as we move into fall.
I glance up the hill about 30 feet and see a cloud of yellow jackets. I accidentally drove over their nest on an earlier pass but my panic turns to curiosity because none of them chase me. (I've had painful encounters with these guys and avoid their nests during the warm months. They often have 3-6 fighters hovering 4 inches above the ground entrance and launch instantly in my direction if I get too close. I've learned to remember the site and then make a raid in colder weather when they have all slowed down.)
I've had the same disappearing experience with my ducks. They don't move away from the garden tractor and they don't quack or get out of the way when I drive up until I get out of the car. They keep 20 feet distant when I'm on foot; the Z can herd them from 2 feet behind and they take their own time to move out of its path. Yet, they spot me at 150+ feet when I'm running past on the road and make lots of noise.
The rabbits act in a similar manner. I can pull within 4 feet when mowing, I'm lucky to get within 30 if I'm walking. The groundhogs have the same pattern.
There was an obscure operant study several decades ago wherein pigeons were trained to peck a key adjacent to an image of a person. They were next given a choice of pecking a house with or without smoke. They all went for the smoke the first time! It's possible that cars are so new that other critters haven't evolved coding mechanisms to associate them with people. Likewise, for garden tractors. Put me on one and I'm invisible. (1)
I had no fear about driving over the nest again. Still, I'm not so curious that I got off the tractor to test my hypothesis about the bees. I'll save it for the ducks or the rabbits.
You could use this trick to get some great close-up photographs, at least of animals. A similar phenomenon may occur with deer. I'm curious if the prohibitions against hunting from a vehicle are motivated by human safety or by an urge to keep things a bit more fair between hunters and the animal.