I have no idea why you would find it “stupid” for people to be friendly to each other and to the priest. People are worshipping together for an hour - it might be nice if they said “Good morning” or wished each other well. One might say “Good morning” when you enter a business meeting, and Mass is just a meeting of a different sort, for worship.
I will try to put this in a kind way, but for you to say that saying “good morning” sounds “stupid” sounds a bit rude, and like maybe you have trouble interacting with people socially. I am speaking from a US perspective where like I said people say “good morning” regularly, but I don’t think it’s just a US thing as I work for a European company and have many meetings with people from Germany, Europe etc and it’s quite normal for people to often be saying Good morning or Guten morgen or whatever when they enter a meeting, even if they are from Europe, not USA.
I would suggest that you try to be less judgmental about these relatively minor practices. It seems from all of your threads that you say negative things about many practices, prayers, wordings etc that many Catholics take for granted as being a normal thing. You may want to do some reflection on why you have these reactions instead of just feeling neutral about it.