Doctors have a much lower threshold for diagnosis of "sick people" because if they miss anything, they can get sued for malpractice (founded lawsuit or not). Even if the lawsuit is completely without merit, most lawyers will settle instead of clearing the doctor with a full trial due to cost. So when the threat of lawsuit is over a doc's head, good medicine goes out the window and lawsuit-preventing medicine goes into full effect.
I realize not every doctor is actually good, and that they can make egregious errors and need to be corrected. Enact tort reform, cap damages, and actually encourage preventative medicine instead of paying lip service to it and you'll get lower costs and better yield for the non-sick 999.
I don't expect a doctor to start caring about the other 999 until that 1 possibly sick person can't sue him and take everything he owns.