Why are there law that determine what a health care worker can and cannot do?

Answer 1

Public safety -- which is the basis for most laws.

The actions of a health care worker directly impact the wellbeing of patients -- and for that reason, the professions can be licensed, and the actions regulated for public safety.

Answer 2

In what way do you mean? Like can a nurse do diagnosis? No, that is what a doctor went all those years to school to do. You will need to be a little more explicit.