Originally Posted by
Davvidd
Yes they have the records of course by scanning. But the reason why it is stamped on the passport is to clarify the date of entry and hence the date the visitor has to depart legally. The Visa does not give any dates on it.
I think they may/must rely on honesty. Certainly more than a few years ago, visitors to Canada not requiring visas only required an initial stamp in the passport. No stamps required on subsequent visits.