Part of the point is that if physical cash were withdrawn then you would _have_ to depend on some private (i.e. non-government) third-party for your financial t

Part of the point is that if physical cash were withdrawn then you would _have_ to depend on some private (i.e. non-government) third-party for your financial transactions. (Obviously you could claim that you already are dependent on them, but there's a difference between a de facto and a de iure dependence.)