not having near-level boarding, ...
The first is fixable at most stations,
Disagree. THe class I's do not want this and will require obscene capital costs to do so - switches, platform tracks, etc... which are either grossly expensive and sometimes not possible to fit. Then you have to dump all the Superliners, Surfliners, etc... Most of Europe has non-level boarding, which is about the same height in step-up as a Superliner or Surfliner.
And it still doesn't fix the real problem. If you board a train in Detroit, they lock the platform doors until the train nears. Then they crush load everybody up the stairs and stop them halfway up the stairs with 100 people in line carrying suitcases. Then when the train stops they try to sort the passengers at some sort of defacto gateway. This sucks. Nobody enjoys it. It is not safe to stop people on the stairs. Somehow Delta and Metra and LIRR and United and DB and LNER and all the legacy roads that had passenger trains all have figured out how to board passengers without officious idiots making their own decisions on account of absent management.
As i have said before, this is a zero dollars problem. Create a standard, publish the standard, enforce the standard. What does it cost to put laminated PDF's in the vestibule of every Amfleet and Horizon in the fleet? $200???
The new Acela: It's not Aveliable.