Fast forward 50 years (once the demographic collapse has fully hit Asia and Europe), and we'll see if their infrastructure continues to be so modern.
But Tokyo infrastructure felt basically as old as NYC infrastructure to me (a totally qualitative impression).
That said, Tokyo is massively cleaner and nicer than NYC even if some of the infrastructure seems old. There is no question it is nicer than NYC.
In part because it is, most of Tokyo's major subway lines were built in the 1960s to 1970s. Ginza line was built before WW1 and was the first subway in Asia.
The highways were all built soon after the war too.
Thus part of the issue is age. Japan stabilized much sooner than Korea and built up faster.
A bigger component though is Japan's preference to build new then let sit. Maintenance for visual reasons is rare. Thus combined with the high humidity stuff rusts and molds. You can see rust on iron beams waiting at the JR platform in Shibuya! Literal rust on one of the most high traffic stations in the world with gleaming skyscrappers as your backdrop.
In part Japan feels like a retired country. All the heavy lifting has been done. The mortgage paid. I joke with friends we are young people in an old country. Everything around us is going into the night, and we are just now waking up.
I like it, but I can see why others would prefer a newer country.
NYC's trains are constantly late, always go out of service, are deafeningly loud, incredibly slow, filthy, don't have great coverage outside of the Manhattan core and generally unreliable. Tokyo's are always on time, very clean, pretty silent, have incredible coverage of the entire metro area especially in combination with the bus networks (which also are efficient, clean, and don't hold lower-class stigma), and are super fast.
The lines that aren't underground in NYC tend to be depressing under the tracks and pretty unlivable around them, leading to tons of urban blight; the over-ground lines in Tokyo, thanks to their thoughtful design and reasonable noise level, are often full of shops, restaurants, bars, and walking paths that people actually use, positively contributing to their neighborhoods.
The main thing that feels "old" about Tokyo's trains is just that they look like they were decorated a long time ago or are kinda plain; but from a functional perspective they outclass practically any system on the planet, especially when taking into account the integration into the broader Shinkansen network. They have the best safety record of any rail system anywhere and are economically sustaining. The only major complaint I have is that it's relatively expensive fare-wise, especially considering transfers between different rail companies' lines/buses.
Also, it's worth checking out the pre-Olympics revamp of some lines - for instance Ginza Line (Shibuya station especially) and Odakyu Line (Setagaya Daita-Shimokitazawa in particular) got a lot of station and neighborhood renovations that give them that sparkly new shine.
Aside, I've also lived in Shanghai before - the rail network in China is something to watch, their high speed rail stations and urban networks are very nice as of late, although they need more express lines within city limits (Shanghai/Beijing are enormous so crossing the city by rail takes a long time).
One thing they all pointed out is that Japan is full of what by our standards would be considered semi-antique technology like trolleys from the 1950s and computers and fax machines from the 1990s, that are all still being used, and maintained in really good condition.
Living in Tokyo, do you notice this as well? I assume this sort of commitment to maintenance / "orderliness" must be cultural?
What do the really bad parts of Tokyo look like?
Ikebukuro is the nearest place to where I live that has a reputation for being “dangerous”, with a homeless population and a large yakuza-dominated nightlife district, but by that I mean there’s like 20 harmless old drunk men around in the plaza sitting around, and a high concentration of sex shops - not dangerous at all though by foreign standards (small women can still feel safe walking around at 3am if they felt like it).
The Seoul subway [1] opened its first line in the mid-1970s (8km of line 1). Most of their subway growth opened in 1995 and later, a huge amount post-2000.
The first Tokyo subway line [2][3] opened in 1927, with only 3 new lines since the late 1970s (and barely even any line extensions in the 2000s)
It feels newer in SK because it is.
[1] https://en.wikipedia.org/wiki/Seoul_Metropolitan_Subway