Now that Google insists on a payment method all of the sudden "we need" third-party solutions?! no one had objections about Apple and Amazon doing so, at least Google allows third-party app stores and sideloading.
What makes you think that "no one had objections about Apple and Amazon doing so"? Lots of people did. Lots of people have been quite vocal in their dislike of the so-called "walled garden" practices of various organizations.
Google and Android have generally provided a relatively open third-party alternative to what Apple and others are offering. If the degree of openness is changing, however, then I can see people speaking out against them, too, and possibly looking for alternatives.
I do object to Apple on this issue, but it is a very hard problem to allow 3rd party payments. It creates support issues and we are talking about a consumer device. I think it is a problem they should have solved, but greed is fun.
I am especially dismayed because Apple is forcing app developers to sell app with no upgrades except in-app purchases. When a new version comes out, the consumer either gets it free or at full price. Apple can do this because they don't really care about customer loyalty on that level. As an app developer, you can sell "feature packs", but that is really confusing and a burden.