> However they are currently running at an interest rate of a little under 4% which is much higher than the rate offered on a typical 5 year year fix. This makes them unattractive when you can just perpetually keep re-mortgaging on 5 year fixes.

Renewing after 5 years will presumably get you whatever rate is then? Which might be much higher.

It's always better to get a fixed rate (for the life of the loan) mortgage. If rates go up, you're protected. If rates go down, you can refinance to cheaper rates.

> Mine is fixed for 20 on a 30 year mortgage

In the United States we don't call that "fixed". We call that an adjustable rate mortgage. For example, my mortgage is fixed at 3% for its entire 30 year term and can properly be called "fixed".

People in the United States are leery of ARMs after what happened during the mortgage crisis in 2006-2011 so proper labeling is more important.

Ah so what I meant is that in Czech Republic I have a 30 year mortgage with a rate that is fixed at 1.99% for 5 years, and is then variable (or more likely renegotiated) after that period. I am sure I could have instead gotten a 30 year mortgage with a single rate for the duration, but I suspect it would've been higher than the rate. But if you're at a 2% for 20 years that is pretty great IMO - given that our rates are currently through the roof.