Hi Bunny,
I'm glad you brought up cashiers because there is another pet peeve of mine to be found there!
I can't stand it when they don't say a thing and I am the one who has to say hello. In particular, I can't stand it when they don't greet at all but yet yell crap to their fellow cashier, socializing with them instead of ever acknowledging my presence. I don't want to be treated special, I just think I should get some sort of hello.