Unfortunately being forced to refinance can also screw you over, like it did a few years ago to a lot of people who had it locked in at 2-3% and then had to get it at 5-6% instead, massively increasing their monthly payments.

There are also adjustable mortgages in the US, and as another commenter already pointed out, if rates go down you can always refinance, and you'll have the ability to permanently lock in that lower rate. So I would argue that the Canadian system actually had no advantages at all over the American system.

As far as I know they still have opportunities to refinance if rates go down (get new mortgage at lower rate, pay off old mortgage in full). There are probably fees associated with it, but you aren't necessarily trapped at the high rate for the full period.

On the other hand, in our system there's a real risk that you may struggle to afford your home simply due to rates climbing.