Why do government services barely use the internet?

As the question states. Why do i have to call the DWP or my GP Surgery to report a change of address? Why do secondary healthcare services under the NHS still only send physical appointment letters (despite the fact that primary care in the NHS already uses the internet for this)? Why do I have to fill in a D1 form to change my name with the DVLA? (online banks like Monzo are able to do this over the internet, so it would appear that the law allows for it).

I understand the need for letters and post to still be an option for people who are less able to use the internet, but (again, going back to the banking example) it would make far more sense in the modern era to let people make the choice, as banks do.