Are unions legal in China?
Side note, they could sure use one at that iPhone factory
Yes, but the law works differently in Communist China.
In Communist China, unions are legal, and often membership is required, but the "union" is not operated for the benefit of the union members, nor for the benefit of (and here's the real difference) the local, national and international Union Bosses. The union is operated for the benefit of the few highly placed members of the Communist Party inner circle.
These "Communists" are very rich elites that collect shakedown "partnership" profits from the people who actually built and run the factories (often foreigners).
The unions are operated to ensure smooth, high productivity operations at minimum cost for labor and benefits.
Unions in Communist China protect the state (which is one of the partners in the business that employs the workers), from the workers, and they do a very good job of it, as the workers in China generally perform highly productive, skilled work for very low wages, and very long hours.
Unions in the United States, and Communist China are highly similar in that they are both based on the same Marxist philosophy and Communist principles of organization and operation.
The important difference is that in China the elite don't allow the fat cat local and regional thug union bosses any riches or power, nor do they fund any international union activities anymore (why pay when ya don't have to and the useful idiots will keep on workin' for ya for free?).
In short, everybody in the union (including the bosses) gets screwed (and executed when necessary), for the benefit of the Communist insider elite who are oligarchs in reality, the 1% ultra rich (pretty much like the DemoRat elite in the US).
The important difference is the Commies have learned not to take too much from the factory owners (that would put them out of business and kill the golden goose), while the US DemoRat union thug bosses have not learned that lesson yet.
As far as your worry over collective bargaining rights, there are only two things you need to remember:
Required union membership=Communist tyranny
Required Right To Work, free from union intimidation=Free Market Liberty
Choose one.
My post was a sarcastic reference to US Communists (reference my tagline), not Chinese ones, however, Chinese Communists do operate within the law.