The 14% gap in US population coverage is from Illinois, Nevada, Arizona, North and South Dakota, Maryland, and Kansas not providing data to this registry. Canada is only at 76.5% of their population included. If you're going with the premise that people in the US present with higher stage cancers like other posters in this thread, then it paints US cancer care in an even better light that they are able to have comparable 5 year survival despite their average cancer presenting later and having a worse prognosis.

I have trouble seeing the reason for your argument about mortality. This is one paper that looks at 5 year survival across many countries. The authors may have chosen this outcome measure because it is the easiest and most objective outcome measure we have. Other papers can look at disability adjusted life years or quality adjusted life years. Those measures just were not used in this paper.