The main issue that is related to people who are uninsured is the cost of their care. Even though these people have no health insurance, there are still times when they absolutely have to have medical care. When this happens, they are typically seen in emergency rooms because emergency rooms must treat all those who have true emergency medical needs. This has impacts on hospitals, physicians, and patients.
The main impact on hospitals is financial. It can be very hard for hospitals to recoup the cost of treating emergency patients who are indigent. Hospitals can try to force payment, but it is not always possible to do so. Physicians and patients are put under more stress by this system. Physicians end up treating people for emergencies that could have been prevented with earlier care. They also end up having to refrain from treating non-emergency conditions that they might detect. This is hard for them to do from an emotional point of view. For the patient, it is hard to have to forego medical care simply because one does not have the money to pay for that care.