It can be like any other system where you need some proof of payment. For example passes for roads where one has to pay a toll. To minimize complexity there can be a common pass for a bunch of services: roads, libraries etc. The important thing here is that there must be a way to opt out if needed. While it does shift complexity to billing each service, it removes more complexity from things like the extremely complex tax code.
(It does raise the question if the govt should have monopoly on roads etc. but that a bigger question.)
(It does raise the question if the govt should have monopoly on roads etc. but that a bigger question.)