SFO is still about a half hour drive in decent traffic for most of San Francisco. I've only flown in once, but it took like 40+min in traffic for me to go from there to Moscone. Meanwhile the train station is an 18min walk from Moscone.
LAX, sure, it is mostly surrounded by the city on three sides, but the sprawl there means the vast majority of the city sees 30+min traffic. Meanwhile Union Station there is right downtown and far more central.
https://maps.app.goo.gl/iKfLwgvCpapoCA6R8
It's incredible how your first two examples are such massive swings and misses at naming cities which have airports more convenient for their city than their train stations. In both the train station is more central to the actual city with a lot of people having a shorter walk to the station than most would have as a drive to the airport. About the first city in that list where the airport is actually more conveniently located is Las Vegas but largely because Amtrack just doesn't serve Vegas by train at all. Sounds like you didn't bother actually researching the list at all and just put down some cities that came to mind. Did you bother actually looking where the train stations were in comparison to the airport?
Another example, New Orleans. It is a half hour drive to/from the French Quarter. It is like a half hour walk from the train station to the French Quarter. Assuming the train and the plane arrived at the same time one could walk there from the train station before you even left the parking lot of the rental car agency.
> My point is if you have a substantial sized city that does not already have a large train station in its center
Just continuing to ignore most historic US cites (and the vast majority of the large ones) do have train stations in the middle of the city
> in the same way that if your city doesn't have an airport that you've built up around, you aren't going to build it
Just continuing to ignore the massive difference in land use requirements for even a medium airport compared to a train station. Just look at those Maps links I shared earlier. Look at how much space Penn Station in Manhattan uses. Think we can build an airport like JFK or even La Guardia in that same footprint? How would they even take off/land? Its way easier for a city to build a train station in its core than to put a whole airport with multiple runways and taxiways and tons of hangars large enough to hold a 737. It's incredible you think they're on the same level of scale to build in terms of land use.