The original post was using the Shinkansen as an example to argue that America should be building high speed rail between SF and LA. But if there was high speed rail there you'd still need to park. If the poster wanted to say that travel in Japan was better because they have good public transport so you don't have to park your car near an airport, that would be a legitimate thing to say - indeed IMO good metropolitan public transport makes a much bigger difference than flashy high speed rail. But that wasn't the argument they were making.