I don't think this necessarily has to do with weapons. There are ten thousands of armed German police officers who (number went through the press) shot 85 bullets in 2011 and usually do not draw a weapon immediately.
There are about 7000 armed police in England and Wales. Their weapons are kept in safes in the back of their cars, they need to have a very good reason to be carrying one, let alone actually using one.
I think in the UK, despite the police closing ranks when threatened (I don't think we have this as bad as the US either) an officer that drew a weapon on a suspect that they had no reason to think was armed (and was only suspected of underage possession of alcohol) that officer would be subject to some sort of disciplinary action.
Unfortunately, it takes less training to become a police officer than a kindergarten teacher in the US so we don't see the same level of restraint. IMO we would be better served by a smaller but better trained force unfortunately the federal, state, and local governments all do law enforcement and at the local level there often seen as a way to generate revenue making them 'free'.
In 2010 there were 243k police officers in Germany. Could not find 2012 numbers.