Yes, missing something.... Is this how you generate hot water at home? If not, then you must be subject to that same "western compulsion".
Exactly. Back to original post... my WIFE WANTS HOT WATER: proposing that I should tell her to sit a water bottle on a rock in the sun and wait is potentially dangerous advise.
Sitting water bags out in the sun is probably great for people that basecamp in warm areas. My typical trip is lots of driving in non-sweltering Canada weather and late night stops, usually 1-2 night per site.
The thermous idea is pretty good, I'll probably give that a try this weekend.
I'll probably also add another couple loops and a deflector plate to my 'on-demand water heater' contraption, you never know, it might actually work.