Trains can only get you right next to a very small fraction of the city. The rest of the way you have to walk(I call it the “last mile” problem)

Mostly due to the poor design of the city, yes.

Do we really need to turn this into a discussion of lost causes? Yes, you monumentally fucked up urban design in many parts of your country.

Yes, fixing it is theoretically possible. No, it can't be done in any reasonably small time scale.