You need to remember that Garmin only makes the hardware and software, they don't make the GIS information. They buy that, and it's only as good as the company that makes it.
All Canadian GIS info comes from DMTI Spatial. They seem to be fairly accurate, but many of their maps, especially in less populated areas like here in Nova Scotia are woefully inaccurate because they are working from old topo maps that have not been updated to show changes. There's a road across the lake from me that was straightened over 20 years ago. Google Earth shows the road running as straight as a die, but when you overlay the map, (Google's buying from the same source) there's a huge "s" curve that was removed years ago.
You have every right to be upset. I am too, but not so much with Garmin. They're buying the best they can get. It's just not good enough.