Also things like disabling complex animations, canceling high-CPU background jobs, doing more work on the server side rather than client (trading off latency fo

Also things like disabling complex animations, canceling high-CPU background jobs, doing more work on the server side rather than client (trading off latency for battery life), using less complex but less accurate algorithms, etc. There's a lot of reasons why an app might want to know the battery status, and most of them are for the user's benefit.