> Half the "namespace" of nearly every coordinate system is biased toward the poles. The distance between 89° N, 10°W, and 89°N, 10°E is 38km, but at 1°N, it's 2226km. My system has a simple and clever way to equally represent the dense equatorial regions and the sparse arctic and antarctic regions, and that equals shorter codes.
The "S2" geometry system (http://s2geometry.io/) is what Google Maps and many other large systems use. It has a small bias towards the poles in terms of some S2 cells being slightly larger than others at the extremes but the bias is pretty minimal.
Another system, Uber's H3 (https://eng.uber.com/h3/), handles this problem in an even better way, although it loses some of the benefits of S2, such as having fine-grained cells no longer exactly fitting into their parent cells. It has other benefits however.
One thing missing from all of these system, including W3W, is that none of them have a height component. If I go to a party in a strange condo and need to call for an ambulance, there is a huge difference between being on the first floor and the fiftieth floor of the same building and W3W does nothing to solve this problem.