Pouring reinforce concrete is a entry level skill, the same migrant workers can do the work on 30 story res towers and 100 story prestige office towers (latter also has more skilled teams for steel skeleton / complex building systems etc). RoR also has to factor in wage inflation and access to labour, building out with known demand (per projected urbanization trends) in 2010s when wage was 25/50% of now and surplus pool was large. And of course return will depend on lifespan of investment, which is where I contend the 20-30 year meme number, since that's the only context where lol PRC quality bad, these investment are trash/obviously negative analysis makes sense. The entire narrative breaks down if it's understood these buildings are fine for 50+ years and can be easily retrofitted to modern standards. Lots of shitty USSR Khrushchevka from 60s/70s are going 50+ years, and will likely go past 70+. 20-30 years is an aggressive guestimate if (old) buildings are fully abandoned, left derelict to elements in particulalry harsh environs (i.e. Detroit), but they're not - these projects are managed / on someones portfolio, and have ppl going in doing very basic maintainence even if building underutilized/vacant. I think longevity becomes political liability - the worst kind of PRC problem - if building stock has to be demolished in 20-30 years, within life time of most people, that's within CCDI cracking skulls territory. Underperform by 10 years, and have 50/60 years lifespan, and it'll be someone else's problem because original planners are likely dead. Yes local gov builds to hit GDP numbers but try not to build in ways that spectacularly blows back within their life times because the one's that do don't have happy endings.