This is a very heated issue in the US.
In the US there is no default coverage. Many people are covered by an employers policy. Almost everyone has to pay at least part of that plan, ranging from $50 a month to $500 or so. If a person makes a low enough salary they might qualify for public health coverage, but its got to be pretty low. Many states will cover children. And senior citizens can get public coverage. All of that coverage usually still requires people to pay a "co-pay" for Dr's visits and many have annual deductibles that have to be paid by the individual before coverage kicks in. But hundreds of thousands of us have no assistance and must pay 100% out of pocket.
I don't qualify for any public coverage so I am uninsured, as my employer does not offer coverage. I could buy a policy for about $300-500 a month that would grant me 1 check-up a year and emergency services only. No preventative care, no illness coverage, etc. For that I'd need to spend $500-1100 a month. So I have nothing. If I get sick and want to see a Dr I have to pay out of pocket, usually $150-400 for a typical office visit. An emergency room visit would cost $600 to $2000 (or more if major stuff was needed). If I am in an accident or get a terrible illness I would probably have to sell my home and declare bankruptcy. I generally pay for 1 check up with my ob-gyn annually to the tune of $180.
We do have some new laws ("Obamacare") slowly being rolled out that will change things for millions of people, including requiring coverage and (hopefully, supposedly) vastly reducing the cost of individual plans. These laws are very polarizing and discussing them in too much depth would probably be considered political and probably not a good topic for the forum. In fact this whole thread might be too political...
ETA: Actually if I (or any uninsured person) get a minor illness I do have the affordable option of a walk-in clinic. These are first come first serve offices that can diagnose and write scripts for minor things like UTI's, upper respiratory infections, strep throat, skin irritations, ear infections, fever, etc. The local walk-in in my area charges $80 as a base fee, plus more for any lab fees for tests they might run.