as atc i always greet my pilots.
some of them don't respond
but the majority do.
i think this is not a big problem....
i see a problem when pilots or atc .. use "point" but they must use "decimal"
use " Eighteen" but they must use "one eight"
when they say just switching without repeating the freq .. and after 2 minutes they come back and say "please confirm the freq for XXXxxx"