I don't know if you've visited a place like Hong Kong, but the short answer is this : Those cities are full of immigrants, taking up the badly paid shit jobs.

I don't know if you've visited a place like Hong Kong, but the short answer is this : Those cities are full of immigrants, taking up the badly paid shit jobs. They're all Chinese immigrating into China so "it's not immigration", but only in the same way Polish workers in the UK are "not immigrants" (not meant pejoratively, and frankly I admire what those people in the UK do, they deserve to be treated better than the British treat them. On the other hand, I do understand why the British labour class doesn't like them : they depress wages, conditions, and opportunity). China is a country of 1 billion people. A slight minority, let's say 400 million people, live in the countryside (ie. everywhere except for some 30 dots on the map). Not in abject poverty (certainly not compared to 20 years ago), but certainly making a LOT less money than they do in cities and living in nicer natural environments, but worse conditions. So they migrate to the cities, take total shit jobs, and slowly become part of the Chinese cities. This process has started, but is far from finishing (although I do think it's more than halfway through, but it's got another decade or so before it fizzles out) So TLDR: China is not doing this without immigration at all. It's just that it doesn't really look like immigration for the same reason that the pretty sizable migration out of Chicago doesn't really look like immigration.