Our family have been members for over 20 years. I'd rate their health care as "good", but the real benefit is that we have NEVER had a billing dispute, because almost NOTHING is "out of network". On the rare occasions we've needed non-Kaiser health care (such as ER visits while traveling), we just give the bill to Kaiser, and they take it from there.
When the insurer owns the hospitals and contracts all the doctors, customer billing is almost friction-free.
Healthcare: https://en.wikipedia.org/wiki/Bupa
Media: https://en.wikipedia.org/wiki/Scott_Trust_Limited
Retail: https://en.wikipedia.org/wiki/John_Lewis_Partnership
Finance: https://en.wikipedia.org/wiki/Nationwide_Building_Society
Lots of stuff: https://en.wikipedia.org/wiki/The_Co-operative_Group
Similarly, it makes more sense to have a non-profit coffee-buying employee group to buy coffee (at places that don't provide it for free) rather than pay a vendor to bring it in. But that's not because profit-making is an inherent drain on efficiency, but because the "judgment" that those profits are "buying" ... doesn't add much value.
Not only that but the healthcare industry has extraordinarily high financial and legal barriers to entry.
If there is a company with enough muscle to force themselves into the business, it's Berkshire.
Unlike Amazon and Berkshire, two of the best managed companies humanity has ever created?
> Extraordinarily high financial and legal barriers to entry
Unlike financial companies?
Newman's Own is one interesting (and successful) example I can think of that's an otherwise for-profit company acting effectively as a charity. Are there papers/books about how effective this would be in practice?