It took me years to get used to people going "how are you doing?" and just walking straight past me. To me, it seemed exceptionally rude - I'd stop, and start answering the question, but the person had just walked on. It took a while to realise that in some places it is just a greeting, and much longer to not have to consciously remind myself about that...
It feels to me like these american show masters, who get on stage and greet the people with a "hello, how are you doing" but since he's asking the whole audience, no one answers.