I have carried and used knives everyday since I was 5 years old. I am quite European in the fact that I use my knife to eat my lunch as well as other tasks.I on the other hand think that it is responsible people (particularly men as role models) not carrying knives that is part of the problem we now have. I find it quite depressing when people almost boast that they don't need a knife so don't carry one. In my experience, tools, including knives, are something that one learns to do without if you do not have them. Using this as a justification why no one really needs the thing is an approach that could be applied to an awful lot of things that many people would miss. Need is a terrible yard stick when it comes to giving up freedom.
If knives were seen as every day tools, boring items with about as much status a set of house keys, then they would be less attractive to the youngsters wanting to carry to gain instant "respect". I remember as a teen at school, a peer learned I owned/carried a pocket knife and wanted to show me his "knife". Brought it to school. It was some hideously low quality stilleto-look-alike. I distinctly recall I was hugely unimpressed, it was a useless shape, dull edge, wobbly pivot, and altogether impractical. I had owned and carried a SAK and assorted pocket knives, locking and not, for about six years at the time.
I am not advocating that people, now, carry locking knives or sheath knives just incase they are useful, but I am advocating that responsible people do not leave the field entirely, that they carry sub-3" non-lockers every chance they get. That they take the opportunity to show friends and colleagues that knives can be useful, and not these scary things only used to commit crime.
I work primarily in a office most days, but my tool of choice is a leatherman, and rotate the different models. No one is shocked or concerned, or even cares, most people often buy a leatherman or SAK after seeing me use my knife/multi tools.
Now I have friends in the police, one of which is the lead for the anti terrorism team in Kent. I have talked to all my police friends, and if the person is polite (and the knife is not something stupid), and they have a knife on them, they are very unlikely to do anything.
Now it is an age and the way you look thing, I have been stopped 3 times by police when I was younger. Every time I had a knife on me, and every time I had a reason and nothing happened.
The more interesting time was when I was coming back from university, they didn't care about the Leatherman tool, it was the dissection kit, mounted needles and the scalpels...but again there was a reason and they were quite interested in the lesson I did, I was there for 15 minutes explaining the lesson and what was done...2 weeks later one of the policemen I spoke to was at the university wanting to see if he could sit in on a lesson.