I've recently read that Canada implemented the Entry/Exit Initiative, so the border agency has been collecting information via airline manifests (lists of passenger names with their date of births, passport data, etc.) on who left the country. However, when I return to Canada, I always have to fill out the declaration form which asks me for the date of my departure from Canada.
I'm wondering then, why do they still care to ask? For a counterexample, I never have to answer this question in the EU.