[Faceman]

In Austria the only real effect of the provisional license is that you may not drive with ANY alcohol level. This means 0.01 BAC (because this could be caused by eating apples) instead of the otherwise legal 0.05 BAC.
In addition to that you are subjected to harder penalties for speeding or other offenses. They often result in an expensive re-schooling (and extension of the probation period).

However we can only make our licenses at 18 (probation period is just 1 year though) and legal drinking age starts at 16 here. I think that this way people have learned about/experienced the effects of alcohol and passed their wild days (when it's new you tend to get REALLY drunk) when they start driving.
That's why I'm a bit curious about the US. Giving people a license at 16 but forbidding them to drink til 21 IMHO results in a lot more DUI (and under significantly more influence).