Final answer:
The described payment system is known as a Health Maintenance Organization (HMO), featuring fixed payments per capita to healthcare providers rather than a fee-for-service system.
Step-by-step explanation:
A system of payment used by managed care plans in which physicians and hospitals are paid a fixed, per capita amount for each patient enrolled over a stated period of time, regardless of the type and number of services provided, is called a Health Maintenance Organization (HMO). Under the HMO model, healthcare providers receive a fixed payment instead of charging per individual service provided. This approach contrasts with the fee-for-service system, where providers are reimbursed according to the services they provide. Concerns such as adverse selection and moral hazard are significant factors in the design of healthcare systems and insurance markets, influencing how healthcare incentives are structured for providers and patients.