They generally fall into three categories:
1) Blade length limit for carry - WHY? The knives in anyone's kitchen are nice and long. I can walk down the street with a 24" long hand saw in my hands that will do just as much or more damage than a long knife.
2) Concealed knife length limit - Again, WHY? Same reasons as above. Will a 5" blade really do more damage than a 2-7/8" blade? No, not really.
Automatic knife bans - Here's one which is like "assault" rifle bans. It's all in how a knife looks and is opened - the knife is no more or less dangerous than a non-spring knife. I go shooting with a cop who carries a Microtech auto. One day at the the range, we had an argument about automatic knife laws.
So I challenged him to a knife opening speed test, with me using my everyday carry Boker. We each had to get the knife out of our pocket and open it. Time and again, his blade just barely beat mine without a spring and one-hand opening. A couple of times, I beat him. After six or so tries, I said: "See, automatic knives are no more dangerous or faster and the laws banning them are stupid." He had to agree.
Excellent post, well state and argued. This is how we are rolling back the insanely stupid knife laws.
A fixed blade is even faster.