I noticed quite a cluster on the South American coastline - Brazil-Argentina coastline looks like it's got 4 or 5 that go nowhere but that coastline. You'd think Brazil was stable and prosperous enough that they'd go with landlines.
The population is strongly clustered on some big cities in the coast, the roads aren't super safe, and the terrain around the coastline is not flat, so it's probably just cheaper to lay them out in the ocean.