To restate a few things:
- It is probably easier to get into Canadian Universities from the US for undergrads than vise versa; UBC, McGill and UofT see significant number of US apps. Canada uses much lower boundaries than US: typically 90% for an A the US and only 80% in Canada. This does not always translate well when a student moves to the US schools. Canadian Universities set tuition on the basis of citizenship not provincial residence with Quebec the only (~$4k) exception. Check out McGill requirements to get a better feel for the contrast: https://www.mcgill.ca/applying/requirements/minima/usa
- US medical schools are more numerous and typically there are more choices and ease there. It is also typically easier to work in the US if you get degreed in the US.
- Moving across the border for graduate school is pretty simple.
- Regular Canadian High school is probably more rigourous than US regular curriculum. There is more AP availability in US. AP is not helpful for applying in most Canadian schools. IB is more useful in Canada. AP is better/easier to leverage for University credit once accepted.
- Canadian schools are typically still cheaper than most US alternatives with exception of superstar students and athletes. It is also easier with financial aid and scholarships if the student does not move across the border after grade 12.
These conditions can all change in a few years!
My 2 cents.