We can easily presumes those who have no insurances are the ones without jobs or who simply can't afford it. The 10% figure seems very low for me... What's the current unemployment average in the USA these days? Of those who work, how many have employer-provided coverage? For those who don't have employer coverage, how many actually pay themself for insurance? What about those who can't get private insurance because of pre-existing conditions? What about those who get the surprise of seeing their "full insurances" doesn't cover for the condition they have? You have a certain cancer? They pay just a specific amount and that's it. You requires long term treatment? They pay only a fixed lenght and after, you're on your own...
This isn't the case in Canada. Everybody is treated, for as long as it takes, for the price it will cost, no matter who you are, it won't make a difference. I was stuck with a pneumonia a few years ago and, within about 1 hour, I was hospitalized. A friend of mine had an aggressive cancer. Within a few days from the diagnostic, he was starting treatment and he's now cancer-free since 10 years.