All other things equal you need to make a very strong case for externalities as the market is efficient. So far it's just people saying "planes are bad."
It's entirely possible the externalities of having people (and goods) unproductive for longer periods of time is worse than simply getting them where they need to be.
I'm a bit confused by what you mean by "strong case". Flying emits substantially more carbon dioxide (by more than a factor of 100, IIRC). The deleterious effects of increasing CO2 in the atmosphere are well-documented. Isn't that a strong enough case?
I was worried that was your position. If you still need further proof of global warming and it's deleterious effects then providing proof is impossible.
It’s not practically possible to prove that something is the most efficient alternative – you’d have to exhaustively show that all possible alternatives are worse. It’s more reasonable for you to provide an even better alternative, since you seem to believe that one exists. Once two specific options are named, the two can be compared in earnest.
Without putting a price on the carbon externality the market can't figure it out though. Idle time of workers is a pretty well understood market problem so I don't think that is an externality.
I mean, have you ever heard of tragedy of the commons?
1) All people share one atmosphere
2) Well-reviewed science shows that individual decisions like taking a flight make the atmosphere less hospitable for all.
That type of problem is literally the reason the term externality was coined.
Perhaps a jet fuel tax? If we bring the the lifetime cost of atmospheric carbon recovery and disaster response to flight, might we make air travel with using ICE engines less routine?
The Efficient Market Hypothesis has been effectively disproven; it was proven that it's equivalent to P=NP, and it's very unlikely that P=NP. In other words, if markets were efficient, we could just use simulated markets to solve NP-hard problems in polynomial time. Not surprisingly, that doesn't work.
> The Efficient Market Hypothesis has been effectively disproven
No, the opposite of "effectively". That's like saying you can't plan an effective route because CSP, or you can't use SAT solvers to design things.
Markets aren't perfect, and that's all that proof manages to show. They could still be 99.99% accurate based on that logic. It's a cute thought experiment, not something practical.
It's entirely possible the externalities of having people (and goods) unproductive for longer periods of time is worse than simply getting them where they need to be.