Because they can't track it. Without total control of every aspect of your life they can't make sure you're a Good Person (TM). What if we let the Bad Guys (R) do whatever they want? Won't you think of the children? You wouldn't want children hurt would you? The irony of all this is the people that want sex workers, minorities, and other marginalized communities to live without fear also vote for these policies to keep their Bad Guy (R) under their thumb.
Sic semper tyrannis.