Ok from that point of view I can understand how that is frustrating - you've worked hard to get that qualification - but to snub others who are "only" medical doctors, or doctors in a different field is a little bit daft to me.
I suppose I could get wound up with BT Engineers calling themselves Engineers (I have an Engineering degree) when they wouldn't know what engineering is. However, they may have done vocational training, or acquired some knowledge and have the aptitude but not the piece of paper to state that they are techincally an engineer or not.
I know some titles are revered by many, and I guess that's down to pride - and that's fine. But also, whilst I do not mean to put down other people's achievements, it could be, quite possibly, that others have also worked hard to get what they have and deserve the similar accolade?