Each of your screenshots correspond to a different privilege management application:
* The 3rd party's own UI
* GNOME Screensaver
* PolicyKit
* And a fourth exists, gksu
To be consistent, all apps should use policykit, because it's newer than gksu (as it's still supported, gksu is obsolete). GNOME Screensaver is a different case, as it manages screen lock. Anyway, Ubuntu's pĺan for this cycle is to drop GNOME Screensaver and replace it with LightDM (Unity Greeter).
Each of your screenshots correspond to a different privilege management application:
* The 3rd party's own UI
* GNOME Screensaver
* PolicyKit
* And a fourth exists, gksu
To be consistent, all apps should use policykit, because it's newer than gksu (as it's still supported, gksu is obsolete). GNOME Screensaver is a different case, as it manages screen lock. Anyway, Ubuntu's pĺan for this cycle is to drop GNOME Screensaver and replace it with LightDM (Unity Greeter).