Collaborators were usually minorities, though. Except in France. Then it was half the country.
But you're comparing apples to oranges there. There were a lot of Nazi collaborators because Fascism was a really popular idea set. Most of the collaborators were local nationalists who saw the Nazi's as a force that would rebuild their governments rather than replace them. That was the entire point of Vichy France - for the Vichy, it was supposed to eventually be all of France. I don't think Petain and his lot knew what Hitler was actually planning to do.
With Asia, you're looking at groups of people who deeply traditional, and already deeply communal. You won't really get them to fear communism (there is a reason Asia was so drawn to it), and they will resent any slight an occupier makes. That leaves Korea out of any polite relationship
Indonesia could possibly be made into an equal partner of sorts, but that doesn't mean much in its own. Even if you somehow overcome the hurdles of diverse number of individual cultures, the underdevelopment of their infrastructure, and the rural nature of their local industry, Indonesia still isn't enough to help Japan make a dent in the Chinese monstrosity.
I'm hardly an expert, so I'll take your word for it on the war topic.
Though I would posit that Japan's economy would still be comparable to China's, considering in the real world it took them until the 2000s to do just what you say, with all of the benefits that affords them. Your comparison would be entirely accurate if China was the United States, but as it would stand in the 1980s China would still have a smaller economy than Japan, unless Aaron has somehow ensured economic growth four or five times larger than that engineered under Maoism.
Japan's economy is comparable because the US occupation. We funneled assloads of money into their economy, and as a result they were able to jump into the Asian market and completely dominate it for a while.
And yes, Precipice China's growth is... peculiar. I'll give you that. I suppose the argument to be made is that Hou's Communism is less heavy handed than Maoism and has made better use of individual talents, since Hou's China always came off as being more of a Single-Party Welfare State rather than a full-blown planned economy.
But it doesn't take a US sized economy to swat down a Japan in this situation. Especially since the US was working with handicaps that China doesn't have. Namely, China is right next door so the entire island hopping business wouldn't be necessary.