The telling line on the CRA website when referring to high income filers says: "These filers expose enough income to the top marginal rate to essentially bring their average rate close to the marginal rate."

They may pay higher taxes overall but it is the means they have to reduce, avoid or defer taxes on income excessive to need both legal and extra legal.  Factor this in and see if they are paying proportionally lower rates.  Warren Buffet, spoke out about this when he said his secretary was paying a higher effective tax rate than he was.  I doubt the situation is much different in Canada.

The simplest way to achieve Drucker's belief is through the tax code so his comment is not irrelevant to the debate.  

Any earner paying zero income tax is either being failed by the system or, as a very few of the wealthy have done, have arranged their affairs so as to pay no taxes.