As a Canadian we are used to purchasing travel insurance when we leave Canada because we have a public health care system and don't carry health insurance for our every day medical needs. I have found (surprisingly) many Americans think that their own private insurance will cover them outside the US. Maybe its because they are paying for it and don't realize that it doesn't carry over into another country. Additional medical insurance when leaving your home country isn't optional its a necessity.
This tragic situation is a good reminder to ensure that you always have medical insurance when you travel.