I think we could eliminate it if literally everyone put in a fairly minor effort - getting vaccinated, masking, washing hands, avoiding gatherings for a while.

Even in countries where the culture is to wear a mask when you are sick I guarantee significant minority selfishly ignores those practices - more than enough to spoil it for everyone else.

Also, masking helps lessen but doesn’t prevent the spread in all cases. Many of the cultures that mask when sick do so because they are going to work or are out and about while sick. The more time you spend with someone, the higher the chances of transmission even if you are both masking.