I can see where something like what3words would be very useful in situations where there’s no handy street address – like rural areas – or when you have limited communications. Lat/long, while covering the entire planet, requires a lot of numbers to get 10m accuracy. (I lived in west Texas for several years. Our address was a mailbox on a route number, and yes, we could get deliveries there from commercial companies – but we had to describe the location for them to find it (two miles west of a and two miles south of b, on road n); they’ve implemented house numbers since then, to make it easier for emergency services (such as they are in the rural areas), but it’s still necessary to tell people where it is.