In your first example, I suspect there was probably other things present you weren't made aware of. Currently the requirements in Canada include (only copy those relevant to your example).
-have a serious and incurable illness, disease or disability (excluding a mental illness until March 17, 2027)
-be in an advanced state of irreversible decline in capability
-have enduring and intolerable physical or psychological suffering that cannot be alleviated under conditions the person considers acceptable
Yes, I know very little other than that he was a cancer "survivor" - he wasn't about to die of cancer imminently but I think he had some sort of long-term ongoing health issues. But he was apparently well enough to drive a car!
The "alleviated under conditions the person considers acceptable" clause is very broad, but doctors have to first agree that the person is suffering intolerably, so it's not entirely a blanket clause.
-have a serious and incurable illness, disease or disability (excluding a mental illness until March 17, 2027)
-be in an advanced state of irreversible decline in capability
-have enduring and intolerable physical or psychological suffering that cannot be alleviated under conditions the person considers acceptable
https://www.justice.gc.ca/eng/cj-jp/ad-am/bk-di.html#s1