* What if you live at an apartment?
* What if your address doesn't correspond to a fixed physical location, like an APO?
* Aren't the city and country redundant if you have a physical lat/long location?
Still, we need to look at how we send information to our fellow humans. Addresses are important and I'm glad folks like the OP are taking a closer look.
apartments need a z value as you already have a x and y - of course you need to account for height above sea level if you keep to the same type of measurement as lat and long (rather than just saying floor 2). It could be tricky for someone to sort that out for themselves.
I'd think a prefix on the address could indicate a special case that needs to be handled differently to fix APO etc.
I played with the demo, it seemed like the city/county operate as a checksum so you can verify the location you've decoded. Its not needed but nice to have