Maybe in Germany these are matters of principle. In the US they are matters of practice. Since the practice is really very uniform, arguments of principle by people who don't know the practice are beside the point.
Americans regularly address physicians (including osteopaths), dentists, and veterinarians as doctor. Some other groups, such as optometrists, also like to be called doctor and often are. Lawyers formerly received the Ll.B. (bachelor of laws) degree for their postgraduate work; that shifted some three decades ago for the same training to J.S.D. (doctor of juridical science), but I've never heard of a lawyer being addressed as doctor. Holders of academic doctorates are frequently addressed as doctor, though more often (where appropriate) as professor, though it would approach eccentricity if a performer with a D.Mus. degree were identified or self-identified as Dr. Persons without earned doctorates who have been awarded honorary doctorates might, I suppose, call themselves doctor, but, boy, I'd call that being awfully full of yourself.
Except for medical personnel (who might use the title in formal nonprofessional situations), you only use doctor in formal professional situations.