Final answer:
Non-emergency patients who come for service without an appointment are referred to as walk-in patients. They are seen based on the provider's availability and this is vital for uninsured individuals who often delay seeking care. Economic externalities arise when the costs of treating uninsured patients in emergencies are passed onto taxpayers and insured individuals.
Step-by-step explanation:
Non-emergency patients who come for service without prior notification or scheduling an appointment are often referred to as walk-in patients. These individuals do not have a scheduled time to see a healthcare provider and are seen on a first-come, first-served basis, or as the provider's schedule may allow. This is in contrast to patients who schedule appointments in advance. The availability of walk-in services is particularly important for those without insurance or those with limited access to healthcare services which is an issue that is part of a larger discussion on healthcare accessibility and affordability, especially for the uninsured and poor who may postpone treatment until it becomes an emergency.
Due to US law requiring hospitals to provide emergency care regardless of insurance status, uninsured individuals sometimes utilize emergency rooms for healthcare needs that could have been addressed through preventive care. This can result in higher treatment costs when a condition becomes an emergency. The financial burden is then often passed onto taxpayers and those with insurance in the form of increased healthcare costs and taxes. This economic consequence is an example of an economic externality related to healthcare access.