All of this is very tricky stuff, I would just call it shades of grey and leave it at that, no black and white. Similar lore happened in the DC metro, everything was fine until it got to be XX years old and then they jacked up the prices and starting shutting things down all the time -- because the infrastucture was all getting dangerously old (subway fires and such) and so they had to quasi-build-new infrastucture, so that got a guy that basically said "we're gonna fix it and it will be painful but we will still fix it" for example - https://thehill.com/policy/transportation/291651-dc-metro-ex...

The crux of it is, it's generally easy to maintain a pretty new system than an aging one (bathtub curve type scenario like in the hard drives). As such we see China sitting real pretty presently but say 50 years from now it will inevitably be a different tune.

Now in the case of NYC I wouldn't be surprised if some of that had to do with crumbling, very very old infrastructure, and I wouldn't deny either by the same token it had to do with macro-economic factors as well, all shades of grey. First 60 years of operation NYC probably had a lot of "brand new" stuff at any given time.