The issue is thick historical quagmire. Why do physicians call themselves doctors when they aren't? The term doctor in this case implies that you are dealing with a physician. It has been so abused by fringe professions (osteopaths and chiropractors calling themselves doctors, often after undertaking qualifications of minuscule quality and length of education).

The most legitimate use is for a person who has completed a PhD, a clinical doctorate or some other doctoral degree. Personally I think only in this case should you be referred to as "Dr". With the advent of the Clinical Doctorate in physical therapy in the US, and now being taken up countries such as Austalia some of us will be entitled to call ourselves "Dr"

However The term is really more a term of power and status. This is why medical clinicians would be loath to give up the term and why some alternative health professions traditionally adopt the term.

For that very reason I think the term should be restricted to those who have a doctorate. Otherwise it is just a pompous posturing to assign power and status to us. Although the road to better recognition is long and hard I think we would do better to gain that recognition by our competence, and earning respect in society by what we do best: physiotherapy