> Few drive 600+ mi empty or alone.

Is there a study on this? As I would have thought the opposite and would bet that the number driving alone is increasing as more people live alone.

Its intuitive, costs don’t scale to travel per family member when you drive from A to B like it does when you fly.

That does not mean that they have someone to travel with though. It would make sense that more trips in groups are by road. But is that much group travel happening in the first place?

> Few drive 600+ mi empty or alone.

Because if you are going 600+ mi alone with minimal luggage you fly, because it's cheaper.

The point is that it's nonsensical to say flying is cheaper than driving. Its oranges vs apple. Apples and oranges are fruit, flying and driving are transportation. But they're totally different.

1. You're normalizing one cost by the occupancy but assuming the other is single occupancy.

2. The assumption that folks are alone in a car is only true only for short trips, trips that are unpractical and expensive by plane. Folks don't fly 600+ mi because it's cheaper (the fuel isn't cheaper until about 1600 mi), but because it's faster.

No one is saying flying is cheaper than driving full stop. The claim from the beginning was flying is cheaper than driving beyond a certain distance. The point of comparison is what it costs an individual to move from point A to point B. The fact that planes have significantly more occupants is an important part of the comparison. Likewise bus travel is cheaper than either flying or driving.

> Folks don't fly 600+ mi because it's cheaper (the fuel isn't cheaper until about 1600 mi)

There are costs besides fuel. Tolls, wear and tear on the vehicle, food and lodging expenses from the longer duration trip, etc. A 1000 mile drive will cost roughly double a 1000 mile plane ticket.

> The assumption that folks are alone in a car is only true only for short trips

Citation needed

Asking people to drive 600+ miles for business is not a good use of business time, even if it is more expensive, typically.

And when people travel 600+ miles on their own dime, the most common reason is leisure/vacation, which people typically do with friends or family.

> Asking people to drive 600+ miles for business is not a good use of business time, even if it is more expensive, typically.

It isn't more expensive typically, but yes when the value of a person's time is considered it's not even close.

> And when people travel 600+ miles on their own dime, the most common reason is leisure/vacation

Perhaps it is the most common single reason, but that doesn't mean it's even a majority, nonetheless an overwhelming one for that subset.

> which people typically do with friends or family.

Which does not actually require the friends or family to drive with you if you are meeting them at a destination, such as if you live far from a person you are going to visit.

So some fraction of all trips are leisure, some fraction of leisure is with other people, some fraction of leisure with other people involves travelling. Again, no one is arguing that driving never makes sense, only that the cases where flying makes sense aren't a small niche.