The reason why I said it consisted of hearsay by a single person is because... the entire article is nothing but repeating what one person said stated as opinion. I'm not labeling it as such because I think it's wrong, I'm labeling it as such because that's what the damn thing said.
Yet it's a person quoted by the New York Times of 1910, whereas what evidence you have is indirect and thus rather pointless. There are many, many other sources of this out there besides, but are generally either from sources you'd ignore or from books that I hardly expect you to jump up and read (such as Beito's
From Mutual Aid To Welfare State). But if you want a direct source on the costs of healthcare for mutual aid associations, then here's one:
Jewish Immigrant Associations and American Identity in New York, 1880-1939. Unfortunately, you'd have to buy the book to get to the bibliography, but the pages in the area cited should be sufficient.
If you can find a source to the contrary, then feel free to do so.
If you want a contrary source then how about the CDC report I linked to showing that insurance rates were far lower then the levels the doctor claimed decades later. Insurance rates certainly didn't go down during that time frame seeing as it's the time period where working class incomes rose the fastest that century.
Then the doctor claimed decades later? Who? Dr. Morris Joseph Clurman? When?
And yes the AMA did shut down a lot of medical schools. That's because the medical schools were complete rubbish and the AMA was introducing science and peer reviewed practices into the field. Before that you had a lot of "doctors" who were bullocks.
Actually, the AMA had medical schools shut down using the authority of the Flexner Report, which was written by a man who was neither a doctor nor an authority on medical education. From that point on, they artificially restricted the supply of doctors to drive their own wages up, which also had the effect of increasing the cost of healthcare. Keep in mind that in 1910, homeopathic medicine and so on were rapidly losing ground and quacks were finding very little business, AMA intervention or no.