Clearly you have never had any dealings with CRA. In a reassessment CRA can arbitrarily disallow deductions and include income as they see fit. The onus is then 100% on the taxpayer to disprove CRA allegations to the satisfaction of......the CRA. While the taxpayer is busy trying to figure out and find supporting documents for individual transactions that occurred years ago, the CRA has the authority to freeze bank accounts, paralyzing you financially. Their sweeping power would make the Spanish Inquisition jealous. 

If CRA writes off an outstanding tax debt as uncollectible, it is with out a doubt uncollectable. Nothing to do with the Tories as you allege.