Still more on vouchers and equality

Thanks to Tom for this reply.  He asks -- responding to my call for voucher-ization of education funding -- "Why not seek more progressivity in the benefit structure as well as pluralism in options, as a matter of principle (even though this approach is probably even less politically viable than the others we've been discussing)?"

If "more progressivity in the benefit structure" helps to get us to the goal, I'm all for it.  (I suspect, though, that the political realities would cut strongly against such progressivity; we'd want to worry about middle-class buy-in).  That said, I guess (and I have to admit I didn't think about this when I wrote my earlier post) I would want to know about the revenue-generating mechanism at issue.  Are we talking local property taxes, state sales taxes, federal income taxes, or something else?  If the mechanism already had progressivity built in (i.e., if the wealthier were already paying in more), then the case for progressivity in benefits seems somewhat weaker.