This reminds me that I had an interesting conversation with a co-worker who has a 13 year old that is the 'only one w/o a cell phone' in her crowd... Not surprising, but what happened to the days when kids had to rely on their own to figure out a way out of a jam like a flat tire? Run into a fixable situation, but too lazy to fix it yourself? Call someone on the cell phone!
I think the consensus on this forum is that riders should be as self-sufficient as possible when it comes to such "emergencies" as a flat tire. Sure, I carry my cell, but only because I'm soloing on country roads and if for some reason I should fall and break a leg (heaven forbid), I have a way to communicate back home for help or to let the family know I'll be a little late for dinner and to start without me...
A flat tire? That's what an extra tube, patch kit, and CO2 cartridges (or frame pump... your preference) are for.