Ive been caught out on the wrong side of a Canal before now, again the map showed the cache one side and the cache being the other... cest la vie
What you need to remember is, and be prepared for the shock.... maps are not accurate, certainly not as accurate as GPS.
Its wrong to say that this is a problem, but the 'problem' is that maps predate GPS, and were initially made by cartographers using very primative instuments, among which included note pads and tape measures.
back in the times when these maps were initially made and indeed up until recently the navigation equipment we were using then were the likes of the compass, so the maps were more that accurate enough, and these inaccuracies didnt matter.
However, GPS has changed all this, now its possible for a computer to plot a point on a map 'accurate' to 1M, and for the GPS to navigate us there... and all too often we find that there are differences.
The thing is the Map, computer, GPS et al are just tools, and the important thing is to learn to use them wisely, and to recognise situations where you may need to test the water a little before committing rivers are always a good example, cliffs are anotehr, now may times has a cache been mapped to the top of a cliff by a computer map, only to find that in reality its at the bottom!