What prevents a proxy-net from starting up and flubbing the recipients/senders of the data such that the ISP can't see what site/domain the traffic is coming from and can't enforce their 1s page-load "tax" on them?
Well, first that would itself impose a page-load tax.
Second, ISPs could just impose a page-load tax on data where it couldn't verify that the source was a one not subject to the tax, instead of imposing it on those that they could verify were subject.
Second, ISPs could just impose a page-load tax on data where it couldn't verify that the source was a one not subject to the tax, instead of imposing it on those that they could verify were subject.