If we are going to use the GPS analogy, not every trip is a route or even paved. GPS is notoriously unreliable when on a hike. You have to be a lot more careful than that.
Most real world software tends to be exactly that kind of situation. You need the rest of the business to help decide every detail of a service that will be in production long term. You are not just on a hike. Business is conquest. You are setting up camp with the lofty goal of scaling to a settlement, then a town, etc.
This sounds dramatic, but I think many are too easily impressed/jaded. Some people can't believe it, but this is still very early days for software. We're barely at the point where, maybe, the layperson can just about build small trivial gadgets for themselves. Meanwhile, there are people out there sailing the seas and beyond.