Men do not believe as a dogma that God would throw a thunderbolt at them for walking under a ladder; more often they amuse themselves with the not very laborious exercise of walking round it.
It almost seems a cognitive dissonance; it probably wont happen, but maintaining the superstition is a maintenance of respect for an unseen order. Actually going under the ladder is an act of defiance that one will likely survive, but sets one at odds with the gods. No one wins. Better the humility and wink at the gods that we all know our place.
Also better to have a horror and pain you can count on, than the irritating niggling troubling question without end. Even though worse than it was before, the mind can rest on something solid. Painful, but comforting.
