And give vague answers with little meaning.
There are knife control laws.
For instance, in California
"Every person who possesses in the passenger's or driver's area of any motor vehicle in any public place or place open to the public, carries upon his or her person, and every person who sells, offers for sale, exposes for sale, loans, transfers, or gives to any other person a switchblade knife having a blade two or more inches in length is guilty of a misdemeanor."
And knives can be used for non-killing purposes such as cutting food, carving wood, skinning animals, opening packages, carpentry, plumbing, painting, fishing. etc.
And many guns have other uses than killing people, like hunting. But machine guns are made for killing masses of people, that's where I draw my little line. It's logical.