And if the driver puts the wrong height in we're back to square one, it doesn't eliminate human error.
This is an argument based on the principle that if a solution is less than perfect, then it is worthless. It's known as "The best is the enemy of the good". This is not an attempt to
eliminate human error, but to
reduce its effects.
If we assume that no driver really wants to hit a bridge, they have an incentive to input the correct height. If they have hit a bridge in the past and got a severe talking to, been disciplined or been dismissed because they have cost the company money (out of their company bond or due to increased insurance premiums) they will have an extra incentive to input the correct height.
It being compulsory to use a proper HGV satnav with height warnings would be bound to have *some* effect on bridge strikes, surely, even if drivers only input the correct height 90% of the time, that would result in a considerable reduction in bridge strikes, due to drivers (presumably) getting something like a big red flashing 'no entry' indication on the satnav for unsuitable routes?
Let's put it another way: Do you really think that it's appropriate for an HGV driver or a haulage firm to use a satnav that will
definitely suggest unsuitable routes, due to it being designed for cars? As opposed to using a specialist satnav that will
almost never suggest an unsuitable route unless you input the wrong height?