Government websites shouldn’t use javascript at all. Problem solved.
But just thinking about my tax return can think of a few features that would have to be dropped, or would become more clunky, like some of the client-side validation, and the auto-saving of drafts.
You should try the dlang forums to see what can be achieved if you don’t fetch 2mbytes of JS from 5 different origins: https://forum.dlang.org