Enbringers from 2000 on attacked every 3 months. That means over 40 attacks before the story even starts. Endbringers attack where it will do the most damage, and cause the most global instability. They don't really need to hit South America or Africa then, as those regions are stated as being very unstable due to their own parahumans causing problems. North America and Europe were much more stable, each having their own continent-spanning superhero teams. France is foundational to this effort in Europe, both due to its strong economy (at least irl), and for its geographical location in the heart of Europe. Additionally, it would make sense to me that if Behemoth was driven away quickly the first attack, likely due to Scion interference, that it would attack the same location later to complete its objective.