I'm not sure how to answer that. Perhaps because the process involves providing your details, just once, rather than any details about a drone. And because you get one registration number that you can then put on any drone that you own, including ones that you don't even own at the time of registration. A general characteristic of registering something is that you provide some details about it, and that it gets a unique identifier. I've no clue how you can possibly construe the Section 336 registering process as in any way registering a drone. It doesn't even ask about your drones. So the fact that your registration number is on that drone doesn't mean that you are registered as a drone owner? Sorry - it clearly means exactly that. The number is yours. And they will go to the owner of a recreational drone via that person's registration number on the drone. There is no inconsistency there. No - and you even spelled out the difference. The car has its own unique registration number. The drone does not - it has a registration number assigned to the owner who registered under the Section 336 dashboard. You don't need a license as a recreational user, but any drone that you fly needs to have a registration number. And that number doesn't show that the drone was registered, because it wasn't - it's the registration number that you obtain after registering your details, not a drone's details, on the FAA registration website. Once you have registered you can buy as many drones as you want and put your registration number on them. You don't have to do anything to register them. Well thanks, but in this case I'm rather baffled because the whole thing seems just blindingly obvious. If what I just wrote doesn't help then I have no more to give.
I'm sorry, but I'm not good enough with this to break down my answer with individual quotes from your post, but let me respond in order:
1. I agree with what you say. You provide your details and not your drone's. However, let me explain my thinking here: I think that you aren't required to provide your drone's details because there are no uniform details to ask about for drones. We've developed the VIN system for cars over a period of 100 years. The FAA can't require serial numbers because many drones don't have them. Some are even homemade. Still, they want drones to be identifiable. So the FAA has settled for requiring the same unique number be put on each drone you own.
2. I don't understand your second point. Of course you are registered as your drone's owner. Anything that is registered must be registered to some person or entity (or what purpose would registration serve). But that does not mean you are registered. Your drone is registered. You are the registered owner of your drone, but it is your drone that you are registering. If you don't own a drone, no matter how much recreational flying you do, you don't register.
3. Yes, I agree completely. But, going back to your point, a car is registered, while a car's driver is licensed. The drone is registered in its owner's name, but the owner of the recreational drone is not licensed. It is the drone, just like the car, that must be registered.
4. I think the only logical interpretation here, which is consistent with what the FAA and the AMA told me, is that the only reason more details aren't required for the drone is that there is no set of details that all drones have. So there is no practical way for them to require you to have a separate number for each drone. The fact that the number must be on every drone is the point. With that number on the drone, the drone can be traced back to the owner to whom it is registered. I don't see why the lack of a uniform set of details that would allow the FAA to require each individual drone's details leaves you thinking that the drone itself isn't registered. It is registered and must have the number on it (like a car's license tag). That FAA number affixed to your drone is its registration. They do allow you to use it on multiple drones, but that just means that every drone is registered. Having the number on them means that they can be identified and the purpose of registration is thus served.
5. Again, I agree with most of what you state here. But, again you relying on the lack of details on a drone to surmise that the drone itself is not registered. That is simply the state of things now since there is no uniform system of details for drones. I'm sure that this sort of evolution took place with cars. Cars did not always have VIN numbers, yet at some point registration and license plates began to be required. They didn't take all old cars off the road when VIN numbers were implemented.
I do understand your thinking when you say that because you aren't asked to register the details of your drone that it is you that is registered and not your drone. But that does not necessarily follow. We are simply at an early stage where drones do not have universal details (like serial numbers). Who knows, something akin to a VIN number might be required for drones in the future. But just because it's not there now does not mean that you are not registering the drone. Although others have suggested that I'm just arguing for agument's sake, I am not. Now that you've laid this out, I see your reasoning, but I think that the logic your using is flawed. I'm not saying that your ultimate answer is wrong as I'm still not certain about that. I'm only saying that your reasoning here does not necessarily support the conclusion you are drawing.