> That's also the logic of the "war on drugs".
The war on drugs isn't a failure because it failed to reduce drug use. It probably has a bit. The failure is that it did so only at the cost of massively increased violence, the erosion of civil liberties, mass incarceration and the debasement of the criminal justice system.
Do you predict lobbying cartels turning to violence to protect their business and so many citizens charged with breaking the law that it debases the justice system?
> It may or may not work in this case -- I don't know -- but it will definitely make lobbying less documented and regulated.
It's not as though there are currently such rigorous and effective regulations that everyone follows.
> What are the sanctions for undocumented lobbyists going to be? How will they be enforced, when the Trump administration is so strongly biased against transparency everywhere else?
The change is to who can be a lobbyist, not in the answer to any of those questions.
> His tax returns matter as the very minimum expected gesture in transparency.
Transparency is for what government officials do in office, not what they do in their private lives.
> At present Americans have no idea what the President owns and how he makes money (or maybe he doesn't -- in which case he would have a strong incentive to use his office to prop up the failing parts of his business empire).
If what he does is good policy that happens to coincide with his business interests, that is not actually a problem. If what he does is bad policy then it's a problem independent of whether it aligns with his business interests. Because what matters is what he does in office, not what he does as a private citizen.