The attitude towards the police varies around the country and it's most likely due to the fact that police attitudes vary. Back in the late 70s, many cops in rural areas would try to size up situations and go on common sense. If they found someone carrying a knife and he was nicely dressed and didn't have a violent history, it was a no brainer.
In the situation with the Arizona police and the guy with the Jennings .22 pistol, it was clear that the gun had been there a long time and hadn't been used. Maybe it had fallen out of someone's shooting bag years earlier, but it had no clip, there was no ammunition, the man was dressed well, respectful and had no priors.
The idea that a 4-inch bladed knife is worse than a 3-inch, or that the blade does or doesn't look used is immaterial. It's the guy with the knife that the police should be concerned with. Our national leaders set a horrible example by obeying only the laws they want to obey and ignoring others entirely (like immigration). But if we, as citizens, try that, we'll find ourselves in jail.
I agree that giving police the latitude to charge is probably advisable, unless, of course, the police force is corrupted. I'm still incensed that the police would come into communities in New Orleans, knock on peoples' doors, take their firearms without so much as a writ, and then store them in blue bins to rust and corrode. Then when ordered to return the lawful property, they ignore the courts. Thousands of people lost their prized firearms, while others had them damaged. It's not unheard of for cops to deface confiscated firearms, returning them in two or more pieces, scratched and otherwise damaged.
When I'm stopped by LEOs, I'm respectful and cooperative, but based on many stories I'm hearing about in the media, there are certain parts of the country where I think I would dread a run in. There seems to be an ever-growing trend against people having any sort of tool or device that can be used for self defense, and the police seem to be following that lead. That's why I posted this question in the first place. The ancillary discussions posted here are only cause for more worry.