It is I think rather ironic that Sue Bonney of KPMG, whose trade and income as a tax adviser depends to a significant extent on precision in language, failed to say what (I think) she meant, which I am guessing was something like:

The volume of tax legislation is huge and its meaning is often opaque.

However, I agree with what she originally said, the meaning of which is that those who interpret tax legislation often do so in an opaque manner. And as a tax adviser in a commercial law firm, I often see tax opinions issued by the Big 4 to our mutual clients many of which in my opinion are of poor quality technically, are sometimes plain wrong and are almost invariably couched in caveats and disclaimers, all of which makes these opinions unfit for their purpose: to tell the client what to do.

In my experience KPMG are the worst offenders here, with PWC running them a close second.