I could see some of the more sheltered cityfolk reacting that way, but you would think people in Washington and Idaho would know better.
My understanding of the law and the intent of "brandishing" is that there has to be some kind of intimidation factor. The environment you are in, the people around you, even the time of day would all effect whether you were carrying, displaying or brandishing, in my opinion.
Even in my case, had this kid not shown previous violent and devious behavior, I would have said "Oh, cool knife!" But as it is, he already established himself as an aggressor and a repeat offendor, so I cannot possibly assume his intentions were innocent.
In the case of this cop gunning down a homeowner, it's a similar thing. They were entering a terse situation, however, as far as I can tell, they not only had plenty of info beforehand, the man also never pointed his weapon at them. As a cop, you have got to be able to assess a situation like that quickly and accurately, and my feeling is, this particular cop just reacted before he knew what was even happening.
As for carrying in restaurants and such, there was a time it might have made me a little nervous. Now I think to myself "That's the person I'm with if the SHTF."