It's human nature to want guaranteed results. And if you're buying a sandwich, a car, or a piece of IKEA furniture, it's absolutely normal to expect a guarantee. If the sandwich is terrible, the car's a lemon, or your melamine-finished GERSBY falls apart, you're going to demand a return. These are products with a pretty standard expectation for the final deliverable.
But the "guaranteed results" thinking breaks down when we get into a service industry. The answer to any que