To be fair to Amtrak, this service is at least new, as opposed to an accelerated existing train. At present - amazingly, to our eyes - the first usable train from NY to DC▸ is at 0903, and the last Acela back from Washington is at 1550 (admittedly there are later Regional Expresses). The distance is equivalent to London to Darlington or Lancaster.
Passenger trains between cities any sort of distance apart in the USA are few and far between - with this "North West Corridor" from Washington DC up to New York with service on to Boston being one of the few where there's anything like a service offering any choice of trains. Albany to New York offers about a dozen trains a day as does San Diego to Los Angeles, but much more typical are cities far further apart and minimal service; the daily train (or eve trains on alternate days) is not uncommon, and certain lines such as Los Angeles to San Francisco have squeezed out the passenger trains completely from part(s) of the route - Thruway coaches take you from LA's Union Station to Bakersfield, then a train to near San Francisco and another road transfer in. There is one train a day via the slower coast line which reduces you to one bus transfer but the direct line is at capacity with long fright trains and a path at speeds that would be required by passengers is not to be had.
Not amazing to my eyes ... but then I have been there and (at first) I was amazed. Cars and flying have rendered the trains very much a minority way of getting between cities across most of the USA.