Problem is, successful amphibious operations might take the Marines inland, and once away from the beaches, they stick out like sore thumbs. There were good reasons why the British army replace red uniforms with khaki and woodland colors.
It depends on what the PLAN-Marines' role is intended to be. Would it be possible that the Marines' main role is to take the beaches? Once the beach head is cleared, the army takes over.
If you notice, only the Marines have the blue camo. Again, my philosophy is that we should give the PLA some credit. The PLA has a looooong tradition of fighting the ground war, especially against enemies with superior weapons. In such conditions, camouflage is absolutely critical. So I would think that the PLA should know a thing or two about camouflage. At least, they should know the basics, like not to use blue camo in a mainly yellow and green background. Don't you think?
So instead of immediately jumping to a conclusion that the PLA has such a low IQ and would make the most fundamental mistakes and make a fool of themselves, we should probably give them some benefit of the doubt. There is something more than meets the eye, so to speak???
This is especially the case when the PLA clearly DO have khaki/woodland camos. So they DO know how to make camo that blend in with the background. And they do know the fundamentals of making camo. So why would they single out the Marines?? Does the PLA hate the Marines and intentionally put their Marines in harm's way and make them more vulnerable? This makes absolutely no sense. So why would they do it and keep doing it? There has to be a logical explanation. Don't you think?