from the wisdom of CorsairMac "don't...count on them having tubes....I carried a CO2 pump, extra cartridges, my cell phone, ID...."

sad but true there are riders who count on volunteer mechanic support on rides for the upkeep of their bikes. When I've needed help, ghost shifting, flats, I got kudos from volunteer wrenches because my bike is clean, lubed, I have what it takes to fix a flat on board (except for knowing how to do it fast).
"this is what one does" I said
"no, riders arrive with threadbare tires, expect to flat, expect a new tire and we run out" they said.

My LBS agrees. I had a Pre-Primavera check up and asked if he has time to check the bike before ALC4. He said that when he offers this to riders before a major ride....and for free...some simply volunteer that "If I have a problem, they'll fix it there".

Stuff happens, things break, can't anticipate everything but it's just more fun when you have the basics to fix stuff if problems occur.

Plus you might not need the tube, might want to help someone else, some cute rider with a flat ;-)

On one Diabetes benefit ride they ran out of food both at the stops and after. That's unusual but it's good to bring some cash just in case you need to "make your own rest stop". Another time was the Healdsburgh Harvest Century which was 104 in the shade that year, we stopped at a little country store and bought bottled water.