Why can't you just label the switches, though? A couple strips of paper and tape are all you need. (Of course, the fact that such a fix is necessary does confirm that something is wrong with the design.)
I wouldn't even say that it confirms a problem with the design, just that it probably wouldn't be a bad idea to have the thing labeled in the first place.
If his sole reason for disliking this particular interface was that he couldn't remember which switch was which, I too am quite surprised that his first thought was to have a new countertop switch installed rather than stick a label on it or grab a sharpie.
Tangential anecdote - someone in my office went label mad mid last year. I made the observation that anybody who needed a label to know that the only light switch in the meeting room was, indeed, the light switch for the meeting room, was too dumb to benefit from meeting with us anyway.
My kitchen has a switch on a little stub of a wall, the other side of which is part of the living room. The living-room-side switch controls the kitchen lights, and vice-versa. It makes sense when you realize that you can use them to do a sort of "airlock" process, turning on the light in the room ahead of you, entering it, then turning around and switching off the lights in the room behind you.
How often do you read a label before switching on a light? I work at a building that has a big panel of them, and I still just flip them on and off until it looks right rather than read the label.
When it's a matter of handed-or-maimed, don't rely on a label!
If his sole reason for disliking this particular interface was that he couldn't remember which switch was which, I too am quite surprised that his first thought was to have a new countertop switch installed rather than stick a label on it or grab a sharpie.