There is no fix per se, other than the mapping companies to do a better job with their maps. If you surf the various GPS forums you'll read that the same type of complaint has been aired by folks all over the U.S. and Canada. Common complaint is: accurate maps in some states, not so good in other states, some areas outdated and others very current.
Once you get outside the continental U.S. the consistency goes down hill; my TOPO3D map with my Meridian Gold is very good for the Vancouver area in general, but when I got the mapping program it was already 2 years out of date the minute I opened the box.
The general feeling I get is that the two main mapping companies, Tiger Maps and I can't remember the other one, concentrate on their main U.S. market and not so much on other parts of the world.
Not surprised for you to find that we Canucks have "moved" our highways from where the maps say they should be.