What Everyone needs to realize is that the underlying data with all navigation systems (GIS) Is constantly being updated. It's not only to update points of interest, but to actually update location of centerline and points on maps vs lat/Lon. This data has different formats and as gets converted to the different applications.
Now when you take into account that there are hundreds of millions of points and centerlines that go into any navigation system, multiply that by the number of different suppliers that provide that combine to collect the data and you can easily see why errors with pop up. Few companies have the resources of a Google and can afford to drive the country for proper location information. Most of the data is a collection from different sources, these various sources can also introduce errors. I am not making excuses for the companies, just pointing out that there is a quite a bit of data that goes into making our NAVs fairly accurate. Of course if you live in an area where streets and addresses are changing more often than the data becomes even more important and dates quickly.
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