Eratosthenes proposed a global coordinate system 2300 years ago, that was flawed but in the next few centuries it evolved into the Latitude & Longitude system much as it exists today after ongoing important refinements like moving the prime meridian to its rightful place ;-)
All the other systems are inferior and only cause to confuse. They do have niche applications but are there really any "better" than Latitude & Longitude?. My mapping app gives locations to a very high level of numeric detail, W 0.12456246 N 51.500661 but it's fine to do some rounding so W 0.1246 N 51.501 gets me on the other side of the road to my intended destination, I think I should be able to spot the Houses of Parliament clock tower from there.
The issue I have is not postal addresses but getting people to meet up at a specified location to go for a walk in the countryside.
In one instance I provided a screen-grab of OS map and Google map, turn by turn directions, UK NGR and Latitude/Longitude coordinates, all carefully double checked and taking them to a parking spot on a minor road. Two of a group of ten didn't turn up, they were a mile away on a main road.
W3W is one of those things that sounds like a good idea until you think it through as discussed above. Useless for me because too few people have heard of it and far fewer have the app. I deleted it.
Distressingly few people understand UK national grid references, some seem to be unaware the the two letters are relevant and will omit them. (And of course they are UK only).
Most sat-navs sold in UK understand UK postcodes as do users but they are hopeless in areas of low population.
I understand some UK sat-navs can take UK NGR (mine can't)
I think most satnavs can take Latitude/Longitude coordinates but that option may be deeply buried and many users seem not to understand or are afraid to use Latitude/Longitude. A friend with a BMW proprietary built in satnav is adamant he can't use Latitude/Longitude (but then he's got a hand-held Garmin GPS device he cant work out how to use either).
Mobile phone navigation apps vary in their location specification requirements.
With dedicated GPS devices Latitude/Longitude coordinates are usually fine except for the variations in how those coordinates are specified. Is it 10 degrees West or 350 degrees or -10 degrees? It is degrees, minutes, seconds or decimal, Is it UGM WTS 84 International or UTM WGS 84 NMEA. And although those devices may have good quality maps, they don't work like satnavs providing turn by turn navigation (sending a GPX route file would be an option if the recipients knew what to do with it.