Those bus networks are the bare minimum in many places, often they are worse than the bus network for example in the rural nowhere of Austria, both in coverage and frequency and connectedness.

To be fair, the suboptimal bus serivce is not even the primary issue. The thing is, that as the majority of urban/suburban areas are completely car centric, public transit simply cannot work effectively. It is by design a crutch that cannot replace the car in many if not most situations. The metropolitan areas are largely designed in a way that transit is so handicapped that it is often only an option without any other option.

I am not talking about what was but what is. The US had a very good PT network in basically any city or even town that was there long enough for that (and there were plenty, especially more or less the entire east coast but als Mid West and even the West Coast, among others). However, the US decided to largely destroy that and destroy its cities to turn them into fully car oriented places. The US did not have to do that, it chose to do that.

I am not ignoring the East coast it is the only place in the US where there are rail based transit networks that feel adequate when compared internationally to other developed countries. Basically all of them however have suffered from either decades or even an entire century of disinvestment. I would only exclude the DC Metro from that. But even that one suffers from the same thing almost all networks suffer: PT is only good for people from further out, if they want to go to downtown but after decades of suburbanisation, most trips are from somewhere in the suburbs to somewhere in the suburbs and even if such connections exist, without big detour via downtown, they often take excessively long.

PS: No one expects a rail service between NYC to LA. That is a straw man really. The East Coast, well scratch that, actually the entire east of the country would be suitable for one big dense network (thinning out towards the west), on top of that the entire West Coiast would be too and then local network in between would make a lot of sense, eg in Texas. Most US cities lie also on well suited High Speed Rail corridors. There is not a single one in existence, one is under construction, at construction costs more than ten times what it costs in most other developed countries (and no, it is not the challenging geography, other countries have that too, most of the money is not even spent on construction). How should one call that if not underdeveloped passenger rail?