Clients lie. This is the one thing that is certain for every contractor in every industry. For some reason, know-it-all clients feel like it's some kind of flex to press their hobby knowledge on someone who is literally a professional in that field. In this case, a pushy Californian client was getting his home remodeled and couldn't fight his manly urge to try and teach his contractor a thing or two...

It's convenient if you're a medieval peasant.

The customer is always wrong.