He's using static reasoning, thats a huge mistake. What if someone stumbled due to misleveling and broke an arm? That would throw the equation off- he needs to understand that elevators do not sucumb to static reasoning, they are very dynamic I had a customer that swore he didnt need a reverse phase relay on a 1925' drum freight car, "why that elevator has run great for years, you're just try to get money out of me!"- is what he told me. Two years later, half of a city block burned and I got pulled into the litigation. The customer lied and said he was never advised of this device. Be carful out there!