As an undergrad I bristled at lecturers' (non-faculty instructors) being referred to as "Professor". I don't believe a title should be used until it's earned. Yet as a student who sometimes examines patients, I'm occasionally referred to as "Doctor" (sometimes by patients, sometimes by physicians). I shy away from the title, although I feel uncomfortable correcting an attending physician in front of a patient. That said, students sometimes try out the title as though trying on a spiffy business suit, incorporating "Dr." into their e-mail addresses and blogs or addressing classmates in jest as "Doctor."
Lots of people are clamoring to be called "Doctor", and a recent New York Times article focuses on some nurse practitioners' push to be called "Doctor" in a clinical setting. Nurse practitioners now have to earn a DNP, a clinically-oriented doctoral-level degree (although it often entails three years of training beyond a bachelors', which would make many Ph.D. students green with envy). The subject of the article is a nurse who introduces herself thusly to patients: "Hi. I’m Dr. Patti McCarver, and I’m your nurse."
I believe Nurse McCarver errs in using the title of "Doctor" in a clinical setting.
First, an analogy. A classmate entered medical school with a doctorate in Romance languages. During our third-year rotations, could he rightfully introduce himself as "Doctor" to a patient? Absolutely not. It's confusing at best and disingenuous at worst. Yet, if the Ph. D. shouldn't be called "Doctor" in front of patients, why should a DNP?
Also, if most health-care providers were to refer to themselves the same way, wouldn't the title lose some of its ability to convey useful information in a health-care setting?
Physicians, optometrists, dentists, podiatrists, and some psychologists can unquestionably call themselves "doctor" when interacting with human patients. I fail to see the need to include some types of nurses as well.
State legislatures have entered the fray, with a handful of states explicitly awarding nurse practitioners the title and a handful expressly forbidding it. So long as this turf war wears on, there will be no shortage of confused patients.