Except when they can cut corners, because "ok, the guy is badly injured, there's some other patient that needs that organ", etc. It's not like they are gonna be extra thorough each time. Humans are known to do that...
- they take the Hippocratic oath very seriously. It's a big part of the culture and indoctrination of medical students.
- they've seen enough examples of people dying from seemingly minor conditions and others of people recovering from seemingly irrecoverable situations to know that their predictive powers are quite fallible
So sure, I expect Doctors to cut corners and make mistakes, after all, they are human. But this is one area where I expect that they're much more likely to err by not declaring death soon enough...
The same doctors in bed with big-Pharma, that shove prescriptions around for money and paid-all-expenses trips?
The same doctors that perform unnecessary operations for a buck?