One of the reasons why obamacare was enacted was to address the millions of people who lacked health insurance.  These people were using hospital emergency rooms for their primary care because they could not be turned away, and hospitals bore the entire cost.   Since obamacare, hospitals have seen a respite, and if you go to emergency rooms, you would notice less of a crowd.

Btw, the full provisions of the individual mandate were never enforced, so proof of insurance has not been required.