Well, to answer to some of your questions and without commenting anything what you have said, I will just ask you:

Do you not wave to the 20,000 immigrants delivering food because:

A.) There are 20,000 (too many) of them or
B.) They are immigrants or
C.) They do not ride road bikes 30 mph or
D.) They are delivering food
E.) Any other reason not mentioned here?

One more question: What do you think in which case, A.), B.), C.), D.) or E.), or any combination of them, is your not commented sentence from the posting before fully appropriate?

I personally do not care if someone waves or not, to me or to other people. More important is why is someobody (not) doing what are they doing, wave or anything else. If the reason is unrelated to me or to other people, let it be their business even if it is just snobbery.