Other countries, I believe, have a joint onus. In our system, the onus is all on the individual. For example, if you happen to not get your T5 in the mail or distributed to you by email but CRA has it, then of course there's an error. You didn't have the opportunity to correct it because you never received the information in the first instance. We can work together. In other words, if CRA takes its role seriously, sends out what it has to and does the best job it can possibly do, the individual then has the onus to come up with the information.
The other part of your question is this, really: What if CRA's interpretation is different from the interpretation you have? We see this all the time with cash.