James Russell: the poor and disenfranchised whose voices "need to be expressed" via a per-vote subsidy are not the ones going to be paying that subsidy: they benefit from the lowest tax rates and may not in fact pay any taxes at all. 
Their share of the subsidy will be borne by the middle class.

If they need to be heard, they  can pick up a pen and write their MP. Postage to the Hill is free.