This is definitely true. These days it seems law enforcement and news agencies seem to use the terms synonymously. It's a very worrying trend because "sex trafficking" sounds much worse than just regular-ole prostitution.
It's possible that moving it off the street has made it so much less visible that these kinds of myths have developed about it much more easily. When hookers were out on the street corner it was a nuisance, but people could see that it was mostly voluntary. Online anonymity has made it more frightening to some.