Note that GPS can be often unreliable or not precise enough. For example, it would be pretty useful to specify correct side of river/road/railway. Arriving at wrong side may result in needing to do very long detour.
True, but no pure coordinate encoding system is going to help there. You need the user to be able to read a map of some sort to:
1. first verify that the position reading is accurate at all
2. adjust the reading appropriately
3. note any further navigation issues that could be important to people trying to head towards them (even with a 100% accurate position that could be a problem).
The selling point of W3W is neither accuracy nor precision, but the claim that it reduces transcription errors that might send rescuers off in the wrong direction – for instance the difference between OSMAP references 680287 and 680278 putting you on the wrong side of the river with a few mile trip in either direction to get to the other side due to where crossing points are (there are no doubt better examples than this, I arbitrarily picked an example close by where I often run). This claim is disputed by a number of people some of whom make a good case (for instance https://www.bbc.co.uk/news/technology-56901363) and the fact that W3W has often chosen to respond to criticism with legal slaps instead of technical explanations suggests to me that the criticism is right.
