I disagree.  Tax departments of large corporations are staffed with professional accountants who have relatively good prospects for employment elsewhere and are less likely to endanger their livelihood and professional designation for the sake of enriching a corporation (plus, usually amounts being assessed on audit, even though possibly in the tens of millions, are still small compared to a large corporation's other cost centres).

While large corporations and their tax advisors often disagree, in their own favour, with the CRA on the interpretation of a certain section of the Income Tax Act, the biggest actual cheats who knowingly advise their clients to commit tax fraud are small firms, who are willing to roll the dice that their client is never audited and even if he is, the penalties are relatively small.  They know the CRA is not going to pursue small firms in criminal court.