I don't carry a knife on my person, but I keep one at my office desk and one in my car. Of course, my kitchen has quite a few, my workshop has several, and my hobby desk has those pointy-sharp X-Acto knives that tear flesh with abandon.
The one at the office has been with me since I was about 11. It's a venerable Victorinox which has long since lost the red plastic covers. It's blade is concave from careless sharpening, and it has peeled a few thousand oranges and nicked many more bananas. I bought a replacement once... and never used it.
In Canada, I could carry a knife around. Many people do.. some even carry Bowie-type (hunting) knives, but they aren't common. I just haven't found a need to carry it constantly. A Leatherman-type multi-tool, maybe. Office workers have little need for such things on a regular basis (although, when I do need a tool other than a staple remover, I can't find one!).