That's well understood, but I would argue that it doesn't always matter (such as in this case, where customers are choosing which service to use), because to many it's not how they see the cost equation.

In short, it doesn't matter how much value Google derives from the transaction, but how much the client feels they spend on it which determines whether they think it's a good deal. If people feel the cost is free, that's what will go in to their internal calculations as to whether to use the Google app or a competitor, and when n comparing "free" to some small cost.

Google gets away with not always having the best app for a service with the trick of looking free, even though strictly speaking they aren't always.