Neither does the US since the passage of ACA in 2010:
https://www.healthcare.gov/coverage/pre-existing-conditions/
My experience is anecdotal from close relatives in Alberta having severe diseases early in life. Their drugs and "required care" was expensive and not entirely covered by their private insurance. Their private insurance had caps (annual and/or lifetime), and after, their medical history made it difficult or impossible to get private insurance with adequate coverage.
The bills were significant, but maybe each province has programs to cover the difference for those that cannot afford the bills?
Some people with chronic conditions that fall through the various provincial drug plans are spending fair chunks of money on prescription drugs that may be necessary for them to have a good life.
For example there is a drug you can take before chemo that reduces the side effects, it costs a lot, wasn't covered by the province and isn't free with private insurance. It can make a terrible experience a little more tolerable.
The Canadian healthcare system doesn’t even have the concept of “pre-existing condition”. That term is deeply flawed and was constructed by the healthcare insurance system in the USA.
The term used in Canada is “medical history”.
I’m at an age where I’m watching my friends in Canada deal with family suffering from long term illnesses and ultimately, death.
They all deal with anguish, grief, heartbreak, and in some cases depression.
But none of them are dealing with medical bills.