Houston is not a mild climate, based on how much AC usage I’ve seen there.

Conditioning an extra 2 to 12ft above your head is absolutely choosing vanity over energy efficiency.

However, most people don’t even have the choice since they’re making trade offs between various neighborhoods of various income levels, and once you get above a certain income, all the houses are made with open foyers and tall ceilings. The builders wouldn’t be able to sell the more energy efficient homes at as high of a price as the non energy efficient ones, so obviously we’re going to end up with a stock of homes where the all the heat downstairs is constantly going upstairs.

The reason the homes with higher ceilings will sell for a higher price is because people feel a certain way about them. A high ceiling has no practical benefits and is purely for aesthetics at the expense of energy efficiency. My intention isn’t to insult, but I think it is accurate. People do many things to project their status.

From a thermodynamics POV, we're very mild. We only ever really want to cool about 20F. Heating is nominal. Most places to the north end up with significantly more expensive heating needs AND roughly equivalent AC needs.

You are still being insulting, or absurdly reductive. Neither is especially welcome. Normal humans value all sorts of competing concerns when evaluating a home where they may spend many many years. Maybe YOU only value thermodynamics and care nothing for aesthetics, but that doesn't mean people who don't share your POV are only trying to project status or whatever other uncharitable thing you envision.

I'm very much in favour of this kind of aesthetic, but having both the heating on and the window open all winter is sad and should be unnecessary.

To be super clear: the amount of heating actually done in a normal Houston winter day is very very minimal. It's just that enough of it collects in the high point of a tall home that an open window is desirable for balance (and, honestly, humidity).