There's several places where only a small ditch separates the two countries.
Is something people say over and over to try NOT to accept bad things happen a lot to innocent people. It's not always in bad faith and I am not saying it is for you (though it increasingly IS online especially), since we are generally taught as long as we are "good" that it will all be ok and that authority are the good guys. But real life proves that not to be the case much of the time and this disconnect is hard for people to accept so they say things like the above...blame victims...call it fake news etc.
Sometimes the story is completely right, but a lot of times they're omitting key details that make it much more sensible.
Did this across a European border by accident. Took us 10 minutes to notice the different style of road furniture.
There's just some small road signs here and there notifying of the need to cross into Canada via the checkpoints on the main roads, but they're often posted where you enter the unmaintained gravel road - not right at the border. These back roads were established long before we cared about crossing the Canadian border. If you happen to be camping or canoeing in the area for an extended period, it's very likely you'll get turned around and accidentally go north instead of south on one of these back roads and find yourself in Canada when you get back to driving.
Furthermore since they're not really well maintained, it's possible you'll be taking turns to avoid washouts or other obstructions like fallen trees. You might stray into Canada just to reach your destination because the preferred route is out of service.