I don't remember not carrying at least a pocket knife, even at school when I was in junior high and high school. Nobody, including teachers/administration gave it a thought. Life was much simpler in those days.
I'm LEO. Been on the job 36 years. Back in the '70s there was a Buck 110 on my gunbelt. Since November of 1996, it's been a Benchmade 401-S. Clipped inside my waistband behind my belt in appendix position. SAK Classic in my pocket for years. Those scissors and nail file are handy. Those two knives are on me every day, all day, on or off duty. Always have a fixed blade of one sort or another in the vehicle. Maybe a USN MK III Mod 0, Busse Boss Street, Gerber Prodigy (currently), something moderately stout, just in case. I haven't needed a fixed blade on the job often, but when I needed it, I needed it.
I've cut seatbelts, cut clothing off victims of various...well...stuff, pried "unauthorized" signs off utility poles, scraped paint transfer off a vehicle involved in a hit and run, cut bullets out of trees or other wood, trimmed my cuticles, sliced fruit (Don't worry, I wiped the blade off on my pants leg before I cut the food.), you get the idea. The same stuff everybody else does. Sometimes, when I need a break from paperwork at work, I'll walk outside the north side of the station, break off a tree branch, and whittle a tent peg or something. Great stress reliever.
Just about everybody in uniform on my department carries a locking folder of one flavor or another. The thing that amazes the crap out of me is the inability of grown men to sharpen their knives. The children are always coming to me asking me to sharpen their knives. I've seen the condition of their edges. They know better than to ask to borrow my knife.
Actual conversation---
Wannabe Adult: "Can I borrow your knife for a minute?"
Me: "What do you need to use it for?"
Wannabe Adult: "One of the screws on my sunglasses is loose."
Me: "Then what you need is a screwdriver. This is a knife. NO!"
I don't remember who it was, and I'm too lazy to backtrack and find out, but one of the previous posters said that if he left the house and forgot his knife, he'd have to turn around, go back home, and get it. I can identify with that. OK, I admit it. I've done it.