but I don't think people are going out expecting other people to have stuff for them if they need it. I think most would just accept there is an issue and walk.
Yup, this. I love riding without a bag full of kit. I keep my bike in good working order so it's rare that I need to fix stuff at the trail side. If something breaks I carry the bike back.
Even though I don't carry much other than a 5mm wrench, twice his year I've helped riders fix their bikes using their tools. Always polite to slow and ask if they're ok.