Has the concept of simple politeness disappeared, or am I just asking too much?

Am I asking too much when I expect the person I just let out in front of me in traffic to give me a little wave or a nod of the head in appreciation? I've found lately that 9 times out of 10, people don't give any sign of thanks when I let them pull out in front of me in a long line of traffic. If it weren't for me, buddy, you'd still be sitting there waiting for some other sucker to let you out. I hope you'll forgive my rant, but I just wonder if this bothers anyone else.