From the same vein that "we're not Google's customers", neither are those Chinese users using a VPN. By leaving China, they're cut off from Chinese businesses who could pay to advertise.
Apple laptops and Android phones are much weaker on all of these fronts.
I don't have a good explanation for why this is so. I think there may not be a good one, other than that complex engineering organizations are very random systems with tons of inputs and changing engineering culture is very hard, and people early in both the Chromebook and iOS projects were able to set and maintain the right culture, and people in the Android and Mac projects (despite being skilled people who care about security!) weren't able to pull it off, essentially by random chance.
Still, your point above stands: a company as large as Apple or Google has too many individuals with their own personal interests for "trustworthy" to really be a meaningful term. I trust Apple mobile phones much more than Google mobile phones, but, for instance, I trust Google laptops much more than I trust Apple laptops. I am sure there are good people working on all four products, but for some reason Apple's mobile phone division and Google's laptop division have consistently put out better products.