And there's no way to tell if you're at the first "point" of the current application(in which case it will switch you to the previous one), or if it will go back to another place within the app.

And the Android OS doesn't determine what the back button does. Individual applications do. So you're dealing with an OS control button that's extremely context sensitive and application specific. You don't know what the button's going to do until you use it in any app.