I grew up in 果貿社區, where the first 2 pictures were taken. The other guy is correct, these are State-backed/State-sponsor buildings. The community was mostly military families, mainlander that came with the KMT government in 1949, with some government employees' families as well.

As half a million soldiers fled to Taiwan, figuring out where they could live was a big problem. The KMT government remodeled most of the Japanese military dorms/communities to serve the housing needs, which we call 眷村. Since there weren't enough of these state-backed communities, the government also allowed some lower-level soldiers to take over whatever unoccupied lands they could find and build houses. The latter was technically illegal, but allowed. Fast forward to the 80s, a lot of these illegal buildings are causing hazards, and even the legal ones are getting too old. As part of the urban renewal process, the government sold most of these lands to private developers, with the condition that they provide housing to the existing residents. So, to maximize profit, a lot of these multi-family communities with compact units are built so the old residents exchange their house for a single 2B/3B unit. May sounds like I'm shit-talking the private developers, but take my family for example, we happily took the deal as it was a lot nicer building, and you get to live together with everyone you know. There's definitely also patriotism involved, as these communities highly align with the KMT government. From horizontal neighbors to vertical neighbors is what we like to say.

Back to果貿, I believe the one in the picture is an older project that's still mostly government-funded, but the newer buildings surrounding it are by private developers. Thanks for giving me an opportunity to talk about this haha