Maybe I should visit the Mercedes / Audi / BMW forums... but my sense is that owners of those cars (recent models with water-borne paint) don't seem to be complaining...
German vehicles are typically coated slightly thicker than Asian/American vehicles being around 100 - 150 microns where Mazda/Honda/Toyota/Ford are anywhere between 70 and 100 microns, where Mazda tends to stay at the lower end of those numbers. So while Mazda does have a slightly thinner paint (on average) than most other manufactures, the key difference is that it seems they don't change this thickness throughout the exterior like most other manufacturers do.
Most manufacturers, from what I can find, vary the thickness depending on the part it's applied to, for added protection. However, Honda and Toyota don't alter theirs much, and I can't see it being the determining factor of how many chips a paint receives.
I still say that driving behind cars too closely results in the vast majority of your scrapes/nicks and, at highway speeds, the difference of 10 - 20 microns isn't going to matter. Could Mazda prevent
some of the chips by adding slightly more thickness to vulnerable parts? Absolutely. But could the driver prevent even more by staying back when possible? Absolutely.