So if -for example- you knew the details of fabrication of your car: you consider that you'd still buy a car with a chassis that was deliberately weakened by an employee, instead of just buying a car with an -unknowingly- faulty chassis?

Why would you accept something that, if not tampered, would be better than the alternative? When there's bad intentions or tampering, you'll have a result that is broken to some degree for sure. If everyone does their jobs as good as they can, you'll only face a chance of something being broken. You can always improve over mistakes, not so much over bad intentions.