Some distinctions need to be made here about manners, I think. Manners is largely social grease to keep interactions working smoothly; it is supposed to be about acknowledging the other person and treating them with some basic and fundamental respect. Real manners, in other words.

The manners you speak of are the hypocritical sort - e.g. calling Trump "Mr. President" even though he deserves no respect in any sort of situation, just because he is "the President". It is this sort of manners where people (i.e. the talking chimpanzees) get upset because social protocols are being violated - the social protocols used to enforce submission, dominance, and status. These social protocols are used to cover up all the bullshit talking chimpanzees like to get up to.