Sat-Nav or Prat-Nav?

Recently there have been a spate of reports about trucks getting stuck in narrow lanes, or people driving into rivers swollen with flood water; all of them blaming the sat-nav.

Here's my version except we expected to have to stop along the route. There are two pics linked together. One the track disappearing into the lake (bottom of page) and the one above of the sat-nav screen.

The route is was telling us to follow is to the right of the black triangle! The black triangle is the car's position and I am in mid-turn to go back the way I came..... The route that goes under the tadpole shaped lake doesn't exist.