I sometimes like to ask this question of med student during interviews, so it's definitely a good one to think about. Basically, I try to get at how tactful someone can be and how true to themselves they are being about becoming a doctor. How much exploration of other professions have they done before completely "ruling out" everything else, while "ruling in" medicine. Avoid the words... "not as good" "not as educated" "less leadership role" - all of those things are individual in nature, not profession.
I, myself, was a PT who went to medical school. The ONLY answer that is completely valid 100% of the time, without insulting a profession is to analyze the day to day tasks of the job... not the profession, but the JOB. What will you be doing that a PA or NP cannot - and saying diagnosing and prescribing medications is NOT a valid answer because they do that... and most do it well. It might be about practice priviledges, but make sure you know what you're talking about before you start to compare.
So my advice would be to call up a PA and an NP and find out what those tasks are that make their days different than the MD's. Who has final responsibility? It might differ by setting. Who does the physical exam? Again, based on the setting a PA might do the whole thing, or only do parts.
Ultimately, I chose medicine over PT because of the following reasons: 1) I didn't enjoy transferring patients or walking with them. I saw the bigger picture and understood the value, but it wasn't what I enjoyed doing. 2) I wanted a greater scope of practice and to understand more completely each lab value, diagnosis, drug and whatever else I saw in the chart. As a PT my education was limited in that sense.
