As we are told, OpenStreetMap is a single global map of the world, editable by anyone and usable anywhere. Mapper in Tanzania has as much say as a mapper in Germany. Cycleways in Philippines can be rendered the same as cycleways in UK. One map to rule them all.
Turns out, not so much. Being that big, OSM is not the same for different countries. We have not one, but a hundred slightly varying maps: here you have different road classification, there you don’t use landuse=forest. Communities are split by languages and territories. Users mapping with JOSM sometimes mock iD users, and vice versa. You cannot build a map of, say, major roads without understanding specifics of every country on the map.
Let’s see how mapping rules and communities differ across the world, and what would you need for your map-based service to be viable globally.