It would be more efficient and civilized to just have a background check with a visum application. That way you won't have them in the us at all. That was the whole point of a visum? Therefore other motives must be behind the desire for full access. Full access doesn't mean people first have to travel or even a desire to travel. It means full access outside the normal law enforcement formula. Useful for many purposes, public shaming, asset recruitment, radicalization etc