In the us system, who or what allocates these resources?

The government that regulate markets and the planning.

Explanation:

The allocation of resources is a plan that uses the available resources of the country on the basis of the friction of wealth and the incomes. It can be seen in the Pareto efficiency outcomes. The organization's strategic planning and the management of the goals are related to the human capital.

Rationing is the controlled distribution of scarce resources, goods, or services. Health care services are inherently scarce: money for services is not unlimited, facilities for delivering services are finite, and health care professionals are limited in time, geography, skills and capacities, and so on