The vast majority of people do not live within easy walking distance of a railway station. And where they do, it is often one with a service that isn't suitable for a long distance journey, e.g. because it starts too late, finishes too early, is too infrequent etc.
But yes I can walk to the station if you want. How's 25 minutes on top sound?
Unless you live in a city centre and are going to a city centre, rail, even high speed rail, and unless your specific journey at your proposed time is subject to a lot of traffic congestion, it is almost never the case that rail will be quicker, even at 140mph. NPR will simply change things from "unacceptably slow" to "in the realms of the tolerable". Rail also has to win in other ways, e.g. a wide seat with a table to work on the way - and that's where reasonably priced First Class comes in.