> 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.