ObBadCarAnalogy: Well, a Ferrari Enzo is more desirable to me than a Skoda Octavia, but I own a bicycle, so there's that.

How many people that bought a Corolla would have taken a Camry for the same price? (Again, not saying that Apple is better.)

This is very close to correct. The better analogy is something like Tesla vs the generic commuter subcompact field. The generic consumer subcompact marketplace is extremely competitive and therefore there are approximately zero profits to be made, whereas the Tesla has one model at one price and basically no competitors.

Want an iPhone, you'll buy THE iPhone for whatever Apple wants to charge.

Want an Android phone, you'll select from a zillion basically identical competitors all more or less profit free (because competitor A can't extract an extra 5% profit if that would drive 100% of competitor A's sales to sellers B thru Z)

This shows the fallacy of "the smartphone market", there's the non-competitive iphone market with about 20% sales and the hypercompetitive confuseopoly market the other 80% buy into.

Even with price parity through on-contract upgrades, apparently not that many. We should expect Apple marketshare to be much higher if the iPhone really is so clearly superior and more "desirable" to any rational consumer.

I do not disagree; but keep in mind that I've never spoken of "clearly superior", only desirable.

Also, since when did rationality enter the discussion? A beloved wants diamonds so their partner buys them. But diamonds are not worth anywhere near what's commonly paid for them.

There is a far mix of rational/irrational behavior in most luxury purchases--it's not an Apple exclusive trait.