I don't think that supports the speculation since as the GP stated, Google is actually doing the opposite of maximizing profits in this case.
It's still about maximizing profit, even when they appear to be reducing it.
Google and Apple understand this well. Since small businesses account for a small % of their revenue, they simply offer a better deal to those small businesses. Now Spotify/Epic Games/Candycrush people will have to argue “but think of the large businesses!” That doesn’t have the same ring to it somehow.
The majority of App/Play Store revenue is protected from government intervention, and profits are maximised. Make sense?
You've chosen a difficult position to argue.