A very simple hypothesis as to why doctors can argue this effectively but teachers cannot is that teachers are not as powerful a lobbying group as doctors.
Doctors have effectively been able to defend their "turf," from hostile encroachment, while teachers have not, not because the situations do not contain substantial parallels, but rather because doctors are politically strong while teachers are politically weak.
The term "Gods in white" exists for a reason, many people ascribe a lot of authority and knowledge to physicians and doctors in general.
Doubting your doctor's diagnosis is usually considered a rather odd thing to do and if it's a doctor of psychology it could even be interpreted as a symptom.
While with teachers it's kinda the opposite; Even tho their whole job is to know and teach things, many people have a way easier time disagreeing with them straight out of principle.
Wonder how much of that boils down to socialization aka in what contexts children are introduced to these professions?
Opposition to most doctors is low, they aren't being forced to be rated by their clients, whereas most teachers have a weak union in a district with poor funding, and thus they have to contend with overloaded classes that result in poor educational outcomes that lead to most students not going on to do much with their lives.
Its much easier to punch down than it is to punch up!
I find it interesting that teachers have a union and doctors have a professional association. I think that distinction goes a long ways in the comparison.
Doctors have effectively been able to defend their "turf," from hostile encroachment, while teachers have not, not because the situations do not contain substantial parallels, but rather because doctors are politically strong while teachers are politically weak.