There were plenty of enthusiastic volunteers in 1984. Children in the story were trained as spies and rewarded for denouncing their parents. Friends denounced friends.

Orwell understood that in order to create an atmosphere of total oppression there could be no loyalty between anyone. This is why the party criminalizes sex for pleasure. It’s the recognition that the loyalty within families is the greatest threat to the totalitarian state.

The government in Brave New World recognizes that as well but seeks to eliminate the threat by other means (taboo and superficial pleasure).