Well the app needs to know where to find traffic data anyway, it could have a different source per region.
That said, I'm not sure whether it's easier to have a big database or a separated one.
With separation, many people could host parts of the traffic data. As a student I could even host something without getting huge costs.
Without separation, you don't have the complexity of splitting per location.
With separation, databases can be smaller and you can put a database with only what you need in that region. You don't want to have requests from Australia being answered (load balanced) to a European server anyway, so if you host Australia's part in Australia you'll have lower latency and a less complex database.
Without separation, you don't have to keep multiple separate databases. It's a simpler, more unified design.
I don't know which is better.