As someone who was quite active in Canadian politics and an observer since that time, I will say that voter lists will never be 100% accurate.

Unfortunately these inaccuracies tend to be ammunition for the losing side to claim some fraud was happening.

In Canada's case, maybe 10% of the 300 parliamentary seats are hotly contested in any election. The results from the other 90% will not be affected by either fraud or poor administration.

There was a good Medium article about how the state of Oregon handles mail-in ballots. It seemed there were a lot of checks and balances to prevent massive fraud. Yes, nephew Pete could send in his Uncle Frank's vote--even if Uncle Frank died a few days before the election. But these kinds of instances will not change the results--even in USA's much closer election races.