A public inquiry must still target certain specific situations. You can't have a public inquiry into tax fraud in general, because that would get you nowhere.
If you are investigating KPMG or Cinar, which caused a lot of people to lose money, you have to target some of the most problematic situations. That way we can get somewhere.
There does have to be an inquiry that will give the commissioner and the investigators sufficient powers to demand the information, otherwise there would be consequences for people who refuse to co‑operate. There has to be an investigation, but it has to be about certain specific situations.