[fragmede]

How does qualifying the definition go from being fine, to being overqualifying? If you want to compare two things, you do have to define what those two things are in the first place. The answer is wheels, because of the many small ones. Toys, office chairs, and luggage. Vs an estimatable quantity of doors because we know roughly how many homes there are in the world. The final answer doesn't become meaningless simply because you've defined the problem concretely. There are many debates to be had, but as to the question of is Europe or America more diverse, the proper response, thus, is: by what metric?

[citadel_melon]

You are playing the doors/wheels game naively because you have already overly qualified your definition of what is a door and what is a wheel without realizing it.

Have you considered for example if ball bearings wheels? Are gears and sprockets just notched wheels? Do cabinet doors count as doors? Do windows count as doors? Do microchip logic gates count as doors? What about pet flaps? Heart valves? Etc etc.. One’s definition of wheel/door can not account for these and countless other grey areas while still being useful.

Maybe one can strain oneself to find a definition that works like how people strain themselves to find a definition of sandwich that includes hoagies but disclude hotdogs, or one can just work backwards from one’s crude definitions and misclassify many objects.

Regardless, there is no right answer if there are more doors or more wheels. The question is too vague. Something that may be possible to answer is a more qualified question like “are there more human-sized doors or wheels for human transportation.” But again now the question is not our original question. And even if we were satisfied with just answering this more qualified question, we would have trouble answering it without a lot of money or making bad assumptions like the distributions of doors/wheels in a given house is uniform across all cities/towns/suburbs/houses etc..