Isn't that because Canada has much lower property taxes than the US? So you have the same effect that you see in California, where low taxes drive up prices.
I don't think spending $6,000 less in property taxes each would justify a $500,000 increase in price.
The math gets trickier when you consider monthly payments. At very low interest rates an extra 500k borrowed might only increase monthly payment by ~1500 which can be partially offset by $500-1000 less in property taxes per month depending on the municipality in Canada compared to US.