I don't know who mfgs CGC's playfields, but CGC's and JJP's are remarkably similar. They both chip very easily. This isn't a design issue....the exact same areas on MM that took thousands of plays to wear away have chipped on MMR at 50 plays in.
I've own several new Sterns and have never experienced any chipping. I will say their clear coats are noticeably thinner than CGC and JJPs, but chipping has never been an issue for me on Stern playfields.
I have restored two machines - a Dr. Dude and a TAF with PPG clear coat. They both have a nice thick layer, a bit thicker than what you might find on JJP/CGC, but nothing crazy. No chipping after hundreds of plays. Both games have several areas that would chip quite easily if they had the ceramic/whatever clear that JJP and CGC use.
So from my experience, this issue rests entirely with the clear coat being used, and despite environmental regulations, it is still possible to secure a clear coat product that does not chip so easily. Just because a playfield manufacturer chooses to go with a certain clear coat, does not mean it's the best one they could be using. None of the major pinball or playfield manufacturers are ISO-certified, so you will get inconsistent quality from game to game. Just the way it is.