2 Planks-- but surely a claims based approach would be extremely bureaucratic. The circumstances of 200 people on a plane delayed by eight hours or cancelled would all be different.
I have been on trains delayed by an hour, got my fare back and felt quids in. I've been on trains delayed five hours, got my fare back and felt undercompensated. It sounds to me like a simple formula system with an element of rough justice would be more practicable. Beyond that it should be up to the individual to take out the right kind of travel insurance to cover them against risks.