Yes it is easier to pay for 30 million people than it is to pay for over ten times that.

And you do pay for it, just not at the point of sale. You contribute 9% of your annual earnings to the national health fund for a terrible public system that leaves over 40% of your citizens supplementing their public health insurance with private health insurance. WHO reports 22% of medical care costs were paid out of pocket as people have no faith in your system. The two main complaints are long wait times and high mortality rates, though those two are somewhat connected and by far not the only two issues.

I could go on, but here's the bottom line: If you think the US should have a series of shitty clinics with limited care and long wait times but are at least free... we actually have those.