Not always. For solo travel, flying can emit less carbon than driving an ICE vehicle, assuming a full commercial flight and depending on vehicle fuel efficiency. For EVs, hybrids, and group travel the calculation may be different.
Also, if you drive, it's likely that the flight you would otherwise have taken is going to make the trip anyway. So you've just added whatever carbon your car emits to the total.
If you're really concerned about it, the best plan is to not travel for pleasure, or maybe use a bicycle.
As you hint, the rule of thumb is that driving is (mile for mile) roughly as polluting as flying. But that's surely the point: nobody is going to drive across a continent to go the beach. The problem with flying is precisely the speed with which the damage is done.
>if you drive, it's likely that the flight you would otherwise have taken is going to make the trip anyway
This is a terrible argument, a straightforward (but surprisingly common) fallacy. The plane is leaving because of the price signal: people bought tickets for the flight. If they stop buying tickets, planes will very quickly stop leaving.
I agree that if we care about the environment then we should at least try to travel less, or less far.
Busses and trains get pretty good bang for the eco-buck. Oftentimes you can bring your bicycle with you for last-mile transportation at your destination city.
Also, if you drive, it's likely that the flight you would otherwise have taken is going to make the trip anyway. So you've just added whatever carbon your car emits to the total.
If you're really concerned about it, the best plan is to not travel for pleasure, or maybe use a bicycle.