why don't these drivers make some kind of acknowledgement that they almost killed you?
Because that's what some of them really want to do? There are some people out there who really hate bikers.
One day this Summer, I was riding around the Madison, WI Capitol Square. I was behind a cager, who suddenly stopped for a pedestrian. Now, I'm all for stopping for pedestrians who are in the crosswalk, but this one was on the sidewalk, and hadn't even started across the street!
I just blew it off to a driver who wants to be extra cautious around pedestrians. However, when we got rolling again, I pulled into the right lane to go around the cager. He cut me off right there, and I had to slam on the brakes. When we rounded the corner, I went into the left lane, and got along side the guy. I looked right at him, and he wouldn't look at me. He knew exactly what he did. He pulled both those stunts, because of me riding behind him.
Another time, a guy was tooling down a country highway in a new, black Camaro. He got behind a couple of other cars that were going slower. He was a fair distance back from those cars, so the first passing zone I had, I pulled out to pass him. He floored it, and stayed right along side of me to the end of the passing zone, and a car was coming from the other direction. I didn't notice he did this at first, because I was looking ahead. I looked at him, and put up my arm, like, "What gives?" He shrugged his shoulders, and kept going.
Needless to say, you gotta stay vigilant.