I don't know. We had one girl in our first aid brigade troop whose mother refused to let her go on a weekend trip in October because she thought it *might* be too cold. This wasn't a camping trip - we were going to be staying in (unheated) bunkhouses, we had several cars, there was a heated lodge nearby, and we were only about 6 miles by road from a small town with a hotel and restaurant. <img src="/images/graemlins/crazy.gif" alt="" />
But there was no question of dealing with this parent - she made her decision and that was that; no discussion.
I wonder if it would help to show them some stories about people who got lost on a dayhike or a picnic and point out that these people weren't "camping", nor were they expecting bad weather.
I think in some ways, it's the same problem with camping and hiking stores. They want to promote the idea of camping as "fun" and "safe", so they (at least some of them, IMO) tend to downplay "survival" in case it scares away potential customers. Whereas the reality is, it is almost perfectly safe - as long as you know what you're doing and are prepared. It's the people who don't know what they're doing, and aren't prepared, who are most at risk.
A friend of mine grew up next door to an Indian reservation and would sometimes visit the families on "the Rez". One time, she watched as a baby crawled over to an open fire and stuck her hand in the flames - watched by the mother and all the adults. She was horrified that they would sit by and allow this to happen - but they explained that, sooner or later, babies will stick their hands in the fire and it's better for them to do it under adult supervision and get it over with, without doing any lasting harm, than to spend years "protecting" them and risk them doing it when nobody is watching.
Of course, with our current "nanny state" mentality, you'd be hauled up on criminal charges of child abuse if you got caught doing something like that these days.
I think the way you explained it to those parents was about the best thing you could have done, in the circumstances.
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"The mind is not a vessel to be filled but a fire to be kindled."
-Plutarch