Being a Dr myself, I don't have to call another Dr. 'Dr. XYZ how are you' etc (when I am Germany).
The problem is - I really don't care if someone calls me Dr. or not (I don't have it even in my corporate email).
And I live in the UK anyway
Austria is very serious on these titles though - like the call many who hold a Master 'Herr Magister xyz....'