The US interstates move military equipment across the country without needing to deal with railroad bottlenecks. It is a public good. Just like GPS, it has ancillary civic functions but it still serves its original purpose.
I mean, that's the de jure purpose, but that's really a nonsensical point to make here. We're not talking about one controlled access route with two lanes in both directions to move tanks around.
We're talking about 10 lane monstrosities, with 8 or more flyovers, standing 20 stories high in places like in Houston and Dallas.
