Tony
I don't mean to be abusive, but you really don't seem to understand how to use a GPS.
Like any tool, it can be misued and if someone chooses to set off under planned, then the problem is their airmanship or seamanship, not the GPS.
It is also part of a suite of nav tools and techniques (including ded reckoning, pilotage, radio nav, vdf etc) and not a stand alone device, so appropriate training on the whole suite is required.
I won't repeat the excellent comments that others have made on good practice in using these aids, but you are starting to sound like an old dog, in a metaphorical sense.
Maybe time to have a think about whether your stance is really sensible.