being prevented by a well designed warning horn.
I have a different perspective; it's pretty hard to design a landing gear warning system, even on an RG landplane, which is foolproof. Remember, "silence is not a warning...".
Pilot of a 177RG I used to rent runs it out of fuel, good forced landing area ahead.... So he runs the checklist - quickly.... [secure engine, extend flaps], select wheels down, then... according to the checklist: "Master Switch -- OFF". So, not only did witching the master off (in accordance with the checklist) disable the gear warning system, but... he'd turned the master switch off before the gear was fully extended. He did not hear a gear warning horn, and did not confirm the landing gear position (he could have hand pumped it the rest of the way. So, he force landed in a really good field, with the gear part way down. They wrote off my favourite Cardinal.
Pilot carries power through the landing, so throttles are never as far back toward idle as the warn switch. When I started flying the Piper Navajo, I found that it seemed to land nicely with power carried through into the flare. I then reminded myself that I was cheating myself out of the gear warning system. So, I made it my habit, after confirming visually that the gear was down, to momentarily pull the throttles to idle, and confirm that the gear horn did not operate. Now silence is not a warning, so that did not count for much, but I had visually confirmed the gear position before doing this - that was my most important check.
One of the C185 amphibians I flew had a really expensive lidar gear warning system - it purported to be able to detect if the plane was over land, or water, and give the appropriate warning of out of and configuration landing gear position. 'Problem is that many floatplane landings are approaches over land, to cross the shore for a water landing. So, no warning, until you cross over to the water, to then get a warning that your wheels are extended - you're going to have to react really quickly then!
Any training I do on RG's will require the pilot to observe the landing gear position, and state it out loud, along with the intended landing surface. Even for a straight landplane RG, it will be: "Wheels are down for runway landing.". Because, even for a landplane RG, it could also be: "wheels are up for ditching", or "wheels are up for off airport forced landing". It is up to the pilot to be aware of the type of airplane that they are flying, and it's systems. There is no excuse for not being able to use whatever visual system the airplane has for confirming gear position, thinking about it, and where you're planning to land, and speaking that out loud. It reassures passenger too!