So if a customer tells a boat builder to put a hatch in the bottom of the boat. The builder should do it because the customer asked for it? That's just stupid.

The installer was a stupid idiot, plain & simple. You don't put an articulating arm into just sheet rock, doesn't matter what the customer wants - it's wrong and doesn't get done that way.

50+ years? So you were doing Audio/Video systems in the mid 60's? Curious what you were installing back then? The only thing I remember my father telling me about those days, was installing a bunch of antennas for TVs. Adjusting TVs. And doing repair work on radios, TVs, etc.