You can't have a switchblade in most states
But you can have machine guns in most states
How tha forget does this make any sense?
If someone is carrying a machine gun down the street, you're likely going to see it and get away before it's a danger.
If someone has a switchblade, they can be hiding it and just spring it out when they get very close.
Much more dangerous. You've no way of knowing.
Plus, switchblades are much much harder for the police/authorities to track down and monitor.
Anyone can get a switchblade.
Getting a machine gun is more difficult and requires some form of authorisation first.
If you were getting a machine gun illegaly and the police didn't know about it, chances are you aren't the sort of person who is keeping it for recreational or hobby purposes.