Android has a way for apps to create and request various permissions via the AndroidManifest.xml file. This is how the list of permissions and features shown in an app's Google Play description is generated. Superuser should definitely be listed there. But currently, no such permission exists to be enforced, which is a terrible precedent:
You can download an app, and without your prior knowledge it can request Superuser access.
After talking with +Ricardo Cerqueira
about this, we've decided on a strategy to ramp up and start enforcing this good practice.
0) Add a new permission with the Superuser, "android.permission.ACCESS_SUPERUSER".
1) The new Superuser will simply warn that the developer is not declaring "android.permission.ACCESS_SUPERUSER" in the manifest. (as seen below)
2) Add an option to Superuser to automatically deny Superuser access to apps that do not have this declared.
3) After 6 months, this option is enabled by default.
4) After 1 year, this is no longer optional (always on).
This is an insanely trivial change for an app to make, and will assist with the transparency of root apps on the market. So there's really no excuse for the developer not to do it!