^^^^
I guess that is a function of the competitiveness within the commercial and domestic markets.
Back in my trainee actuarial days I remember coming across these commercial mortgages (the company I worked for used to lend LOADS to GPs) and I asked a question about switching and then I was told about the cost of the switching penalty.
Your last point is interesting. Let’s say we were in a situation where inflation was high, but the central bank was very aggressive with regards to its monetary policy then we would have a yield curve that sloped down abruptly reflecting how inflation would be squeezed out of the economy. This would make 5 year rates much lower than current rates and mortgage providers should price accordingly.
However, given that most people do not know what a yield curve is they would take the extra margin and slip it in their pocket.
Sorry for going technical. I am just making sure that I can still work through the logic 😆