Those drivers get a more accurate view, but even they don't get as much help as they'd like. While it'll say whether or not they're in surge pricing areas, it doesn't tell them how many other drivers know about the surge and how long it's likely to last. They could easily end up hovering around a busy area without realizing that the surge is over, or finding out that there are already hordes of Uber cars headed into the region.
The company does have reasons to be cautious about giving you accurate data. Theoretically, Lyft or another rival could use these maps to find weak points in Uber's coverage. However, the concern is that neither passengers nor drivers have proper insight into how Uber actually works -- the only ones that do aren't on the street at all.
This article by Jon Fingas originally ran on Engadget, the definitive guide to this connected life.