Jonathan Zittrain thoughtfully responded to my little critique of his article, as follows:

I hadn't thought of linking the undesired complexity of both tax and copyright with a suggested solution that, as you point out, substitutes tax for copyright. I'm still thinking it through, but so far I'm still undeterred. That's because Prof. Fisher's alternative compensation scheme may be complicated underneath -- with a complex set of digital turnstiles embedded at various network points to measure the relative popularity of various instances of music and other entertainment -- but it's still refreshingly simple on top. The question of complexity isn't just an abstract Occam's Razor-like concern, but rather a fear that the complexity of a legal (or tax) code ends up being unfair to citizens -- they can't exercise rights (or hang onto money) to which they are legally entitled, because they can't figure out the system and the cost of a lawyer to negotiate the paths is utterly distortive. If someone wants to make fair use of another work, the cease and desist letter that too often results makes the user err on the side of exclusion, which is unfortunate for them and for the rest of the public that can and should enjoy the new work even under our existing scheme. A flat sales tax or some other gross simplification to the tax code has obvious substantive rawbacks apart from its benefit of simplicity (and absence of lobbyist-inspired loopholes). The simplifications to copyright -- from the point of view of both user and producer -- that Fisher calls for doesn't, in my view, have many major drawbacks, and that simplification on the copyright side would again far outweigh the new (and surprisingly undistortive to consumer and producer behavior) complications on the tax side. In the big picture, libertarian thinking might welcome a way to get the government *out* of the business of enforcing these byzantine copyright rules -- especially since such enforcement is so often are expressed as, for better or worse, restrictions on speech -- even as the ACS brings government back in to maintain the incentive scheme of content production by becoming the arm's-length collection and distribution agent for payment for many works as a whole. Knowing that a libertarian would, all else equal, prefer neither, what's worse, when gov't tells people what they can and can't say (and still becomes a tax collector when it presides over infringement suits), or when the gov't gets out of copyright enforcement but adds a small tax to an already-overflowing taxation scheme?

I expect I will have my own response to his response in a few days.