cash also has a fantastic advantage that no piece of technology will ever have - its ability to level the playing field in terms of access. No government can invalidate your cash without simultaneously invalidating all cash. This is not the case with any digital system.
See here for one example where the indian state denied citizens access to their money by freezing their UPI accounts after unproven allegations. https://www.thenewsminute.com/article/bank-acs-can-be-frozen...