Keep in mind that we (i.e. members of this forum) are by far atypical of most bike riders. We know about and care about bike maintenance and repairs. Most casual riders have the same level of mechanical knowledge about their bikes as they do about their cars; NONE. This as particularly true of the folks you see tooling aroung their neighborhoods on a summer evenings or on the local MUT on weekends.

I also carry two tubes, tire levers, a small multitool, a small chain tool, a chain master link, patch kit, CO2 inflator, a minipump, tire boot material and a small pocket knife. I've used them all at one time or another for myself or to assist others. As I mentioned, this level of preparation is not typical.

BTW, I do carry a cell phone and have used it once in 26 years of riding. I ran over a ring-shank roofing nail that punctured the rear tire, both sides of the tube and penetrated the rim far enough to stick out between two spokes. It was stuck so firmly I couldn't pull it out and I called my wife to come get me.