I mean I think the answer is that good doctors do form employee-owned co-ops, which are often very successful and establish a great deal of trust in their community, but then when the time comes for them to retire they very understandably cash out and sell to the private organizations that proceed to run them for profit first.

I've been playing with the idea for a while that any time a company uses its name, it has to disclose its ownership (first the company at the top of the chain, then the ownership structure of that company). So like for example the company name "Gerber" would have to always be coupled with "owned by Nestle, a publicly traded company.", and "Dave Franklin, a Dentist in your Community You can Trust" would have to be coupled with "Owned by Private Equity Incorporated, mostly owned by pension funds".

This would make it easier to keep track of if the same company is just screwing you over and over again with different faces, while still allowing some value to remain to brands that are consistently good for customers.