Voluntary disclosure will be done by someone who is feeling the heat.
As for international tax evasion, since the Canada Revenue Agency's record in this regard isn't very good, why would someone who has hidden their money outside the country agree to make a voluntary disclosure, when they know full well that the agency isn't going to take the necessary steps to retrieve it outside the country?
So people won't be making voluntary disclosures because they know that they won't be caught and that we won't try to find someone who has hidden money outside the country. So there is no incentive for people to make voluntary disclosures.
There have been quite significant voluntary disclosures in the past, of course. We remember Brian Mulroney, who voluntarily disclosed income several years later and paid half the taxes owing. These are sad situations, but people remember them.
It should also be remembered that the United States has had very ad hoc voluntary disclosure programs. The United States gave people three months to voluntarily disclose their income, after which it was too late to do so. Today, the United States has opened the doors much more and there is much freer voluntary disclosure.
Here in Canada, the measures are now more binding. That's good, but there still won't be voluntary disclosure until the Canada Revenue Agency is more proactive in investigating cases of international tax evasion.