aside from the privacy thing and practical use, cash does have the following major advantage/function: It's the one thing that stands in the way of governments

aside from the privacy thing and practical use, cash does have the following major advantage/function: It's the one thing that stands in the way of governments (or supranational unions) pushing negative interest rates or even harder means to surreptitiously or openly disown citizens via the money itself e.g. as an easy way to reduce the state debt in times of state debt crisis. Of course there are other ways for states to do that (e.g. inflation)… but those come with much bigger other problems and obstacles for any politician who would want to use them.