Straw man argument. I'm not posting in support of the full scope of these laws as applied in NYC or Philly. But I do need to point out the fundamental flaw in your argument above.
The basis of the law is not "you don't need it." The basis,
whether you buy it or not, is that knives can be used as an offensive weapon, with
the exception to their prohibition being for those who have a "legitimate" work need for them.
The "need" part applies to the
exception to the law's prohibition, not the prohibition itself. Attacking the law because you think it's basic viewpoint against carrying a knife is "you don't need it" is, therefore, a straw man argument.
Now, watch as subsequent posters attack me for supporting these laws as written and enforced, which I have not.