In terms of one of the biggest challenges, of course, we live in a self-assessment system where you're expected to file your own taxes and the tax of your corporation. You're responsible for those. A common source, particularly for middle-class small business owners who can't afford a fancy accountant, is to turn to the CRA for answers, and unfortunately, we get the wrong answers a lot.
Coming back to the impact that has on them, that results in improper tax filing, probably, in some cases, diminished revenues to the government, and a very high level of frustration when the CRA figures out that they've filed something wrong, and particularly in the area of GST/HST we see this quite a lot.
In a lot of cases, for people who can't afford tax accountants, the real costs are a sense of frustration, followed by a sense of a lack of trust in the tax system, followed by CRA reassessments because they got something wrong when they tried their best to comply with it.