For example, Kaiser Permanente, the giant nonprofit health plan that also owns physician groups, settled a malpractice case for nearly $2.9 million last year with the family of Ken Flach, a former tennis player who contracted pneumonia and died from sepsis after a Kaiser nurse and doctor would not send him for an in-person visit or to the emergency room, despite the urgent pleading of his wife. Kaiser said medical decisions are made by its providers in consultation with their patients and said its “deepest sympathy remains with the Flach family.”

Doctors also chafe at oversight that does not benefit patients. “They are trying to run it like a business, but it’s not a business,” said Dr. Beth Kozak, an internal medicine doctor in Grand Rapids, Mich.

Her doctors’ group has teamed up with Agilon Health, an investor-owned company, to work with Medicare Advantage plans. Dr. Kozak said she has to work longer hours, not to provide better care, but to supply additional diagnoses for patients, which increases federal reimbursements under the Medicare Advantage program. “It’s not because I’m giving better patient care,” she said. “It’s all tied to the billing.”

The corporate consumption of medical care keeps growing. Walgreens Boots Alliance, one of the largest U.S. pharmacy operations, spent $5 billion for a majority stake in VillageMD, a primary care group, and teamed with Cigna to buy another medical group for nearly $9 billion. And short of an outright purchase, UnitedHealth is partnering with Walmart to offer care to older patients.

In promoting the benefits of buying Oak Street clinics to investors, Karen S. Lynch, the chief executive of CVS Health, said primary care doctors lower medical costs. “Primary care drives patient engagement and positive clinical outcomes,” she said.