DNPs spend more than enough time (counting training and experience) to deserve the "doctor" title
I feel that after spending more than 12 years to become a nurse anesthetist, I should be called a doctor!
Though they're both called "doctors" their degree means something different. An anesthesiologist and a nurse anesthetist (DNP) have the same function but are operating under a different structure. And because nurse anesthetists are more affordable to hospitals, they both serve a valuable purpose.
I feel that advanced practice nurses spend plenty enough time in school to be called doctors.