I used the car down a staircase story because it happens all the time.

[I]t’s possible to sue the government if one gets into a crash due to bad signage.

That's because the government operates the roads.

If you ask me for directions to my house, and as part of the directions I give you, I tell you to walk down a path in the forest where no path actually exists, through pretty serious terrain, and you have no gear to speak of, and you go anyway, you are entirely responsible for having to be rescued and airlifted out by helicopter.

This guy, and anyone like him, is not obliged to follow a map application.