Typical interest rate fixes are much shorter in the UK though (2, 5, 3, 10 year fixes are the most common)
A 30 year rate fix with no prepay penalty is incredibly borrower friendly because you can (nearly) always take advantage of lower interest rates, but don't have to worry about your rate ever going up.
Ex: closing costs for new mortgage in my area average around 5k.
I can opt into a fixed 30 year mortgage, which I can exit at basically any point through a refinance or sale event.
I can't port my terms, but my rate is also fixed for up to 30 years unless I exit the arrangement. That's a safer deal for me than having 5 years of fixed interest and then being completely at the mercy of market rates.
At least for me - I'm fixed at 2.25% on a 20 year mortgage. Which was only possible because I exited a mortgage through a refinance to bring my rate from 4.4% to 2.25%. Right now if I refinanced, my rate would be much higher - so I will defer borrowing lots of money again.
Basically - The US system only feels weird when we experience particularly strong movement in interest rates. If the rate stabilizes at 7%, no one is going to bat an eye at getting a loan at 7%. It's only during this window where 18 months ago I could get 2.25% and now it's 7% that feels off. And even now - it's not off, there are just lots of folks in a position where their current mortgage is now a steal, and selling sucks since they lose the benefits.
-You rent out your home and retain and continue to service your low interest rate mortgage.
-You relocate to new city and rent from someone else with a low interest rate mortgage (and thus, presumably, attractive rental terms).
I predict this will become an increasingly common solution (for the subset of homeowners who need to/want to relocate) and that some sort of new middleman/platform will emerge to serve this market (think longer term residential leases, better vetting of renters, etc)