Discussions

The cbc is making a big report about people who's Canadian citizenship is denied for various reasons. Mostly revolving around conditions for those born outside of Canada. I can understand it being a problem if you have lived in Canada all your life only to discover that as far as the country is concerned, your not a citizen. The cbc however is talking about the matter affecting thousands of people applying for things like passports and social assistance.  
My question is wouldn't this problem have come up for most of the affected people over 18 years of age? Either none of the affected people have been paying income tax or the government doesn't verify your citizenship when processing your taxes. Neither of which makes sense to me. Is anybody with a better knowledge of the system able to tell me if it's possible to go through the whole income tax system, claiming Canadian citizenship, and never being verified?