I will elaborate with an example.
I recently went to the Brecon Beacons and a group of us had to meet up with two latecomers, coming in their two cars.
Their fault for sleeping in they were late, but we went off to have fun in the middle of nowhere, some carpark next to something or other was the meeting point. At one point one of us had a conversation with one of them, which went something like this
us "well, where are you at the moment?"
friend in car "I don't know"
us "are you in Wales yet?"
friend "I don't know"
"How can you not know?"
"well, I just drove along the M4 for a while and then when I did not know where I was going I put in the postcode to the nearest tescos (she works for tescos so had abook or something?)"
"well, how can we direct you here then?"
"what's postcode of where you are?"
"there isn't one, it's a carpark on a hill"
"but what's the postcode"
"don't you have a map?"
"no"
"didn't you print off directions to where we are staying?"
"no"
ummm....
"what's the postcode for the place we are staying, I'll go there then"
"THERE's NO POSTCODE....... " or at least, that postcode covers an area of about a mile. aaarggh.....
Coupled with many reported incidents of people driving off cliffs because the blindly follow directions of little person in box on dashboard, and, and, and..... what does everyone using just their satnav do when they hit roadworks, or a jam,?
I personally look at my map and work out another route, if necessary. I am in control of my journey basically. And if I mess up, I can find the street I am on again, sort it out.
I think all satnavs should be destroyed basically, and that people should learn to read maps again!