These follow the same rules as the reviews: the conflict of interest is stated before anything you might act on, every number comes from the company's own material and is dated, the section on what the app does better is compulsory, and none of them concludes that ours is the one to install.
Why the price is so often missing
Neither app store requires a developer to publish what an in-app purchase or a subscription costs. Apple prints a price only where a developer has promoted one item, Google Play only where a developer has filled in its In-game items and offers section, and a company's own marketing page can name three tiers without pricing any of them. So the answer to “what does this cost” frequently is not published anywhere you can read before installing.
When that happens these pages say so and name the surfaces we checked, rather than borrowing a figure from an affiliate post that cannot be verified and goes stale without warning. An unpublished price is a finding, not a gap.
The reward-app version of the same question — what an app pays you rather than what it costs — is in what they actually pay. Comparisons are in the alternatives, and the games we write about are in the games.