It has long been easy for anyone to buy health insurance without an employer in the US. If you are self employed, you can even pay for it with pre tax income.
The problem is it costs $500 to $2,500 per month per person plus $10,000 out of pocket maximum per year, which means you need a high income to be able to afford it.
But, public hospitals with low or no cost care exist in some of these places, and from my observation, I do currently think it's a contributing factor to why small businesses are more likely to exist. But, it's only one knob to turn.
Maybe free health care would help, but i think its kind of minor compared to other factors.