Before I answer this I want to point out an interesting contradiction your concern raises. You propose that the Chinese government is lax in enforcement. Well, is the Chinese government an authoritarian monster who punishes citizens over the tiniest infraction or are they lax in enforcement of some of the most obvious violations of the law? When discussing China with people I notice things like this. "China bad" wins over common sense. Propaganda works, folks.
Yes, China has actually been working to reduce child labor. The thing with China is they are actually concerned about their image to the rest of the world. Child labor is a blot on them. They still have about twice as many children in the workforce as the USA or UK, but the days where they worked them like they still do in Bangladesh are over and the situation improves year by year. This is not to mean we shouldn't be critical. We should be critical of China, the USA, the UK, and everywhere were children are abused and exploited.