TLDR: Why is the only nurse we encounter in the wizarding world Madam Pomfrey?
Throughout the Harry Potter books, Madam Pomfrey is described as both "the school nurse" and the matron:
From Book 1:
Madam Pomfrey, the nurse, was a nice woman, but very strict.
From Book 6:
He [Harry] had been intending to visit Madam Pomfrey, the matron, in whom he had a little more confidence when it came to Healing Spells…
The Harry Potter series also describes Healers, which seem to be analogous to Muggle doctors. For example, in Book 5, when they're visiting St. Mungo's to see Mr. Weasley:
Witches and wizards in lime-green robes were walking up and down the rows, asking questions and making notes on clipboards like Umbridge’s. Harry noticed the emblem embroidered on their chests: a wand and bone, crossed.
“Are they doctors?” he asked Ron quietly.
“Doctors?” said Ron, looking startled. “Those Muggle nutters that cut people up? Nah, they’re Healers.”
Interestingly, however, no nurses are mentioned at being at St. Mungo's. The closest seems to be the "Welcome Witch" directing people to the various floors:
“Over here!” called Mrs. Weasley…and they followed her to the queue in front of a plump blonde witch seated at a desk marked inquiries.
See also the sign describing her:
If you are unsure where to go, incapable of normal speech, or unable to remember why you are here, our Welcome Witch will be pleased to help.
However, she's not explicitly named as a witch.
In St. Mungo's, the healers seem to be doing triage in the "ER" by walking up and down the rows.
Doing some research, it seems that matrons are found at both schools and hospitals, so Madam Pomfrey's role at Hogwarts seems to make sense. However, why do we not encounter nurses anywhere else? In fact, the only other mention of nurses I could find in the books was the head nurse at Smelting's, Dudley's Muggle boarding school:
The diet sheet that had been sent by the Smeltings school nurse had been taped to the fridge…
It seems that the only nurse we encounter (at least in the novels) is Madam Pomfrey. Why would there be no nurses at St. Mungo's? Do Healers fulfill the purposes of both doctors and nurses?
Tangentially related: It seems that there are conditions Madam Pomfrey is unable to handle, and must send the patient to St. Mungo's for:
- In Book 5, McGonagall was sent to St. Mungo's after being hit by multiple Stunning charms.
- Also in Book 5, Tonks had to spend additional time in St. Mungo's after the final confrontation at the Ministry.
- In Book 6, Katie (after touching the locket through her glove) was treated by Snape, then sent to St. Mungo's.
Related questions: - Healing magic in Harry Potter universe?: Does not specifically deal with healers vs. nurses - In Harry Potter, are house-elves being used as nurses?: Discusses house-elves healing people, but not in any kind of official capacity