Because they cheat. You know it, I know it, they know it and everyone with a trace of intellectual honesty knows it. It's so blatant and rampant that I don't even think a 90% turnout in an overwhelmingly Dem district can be considered a particularly successful effort for them. Several districts in Philadelphia had in excess of 100% turnout in the 2000 election. When they start smashing the boundaries of what's mathematically possible, that's when you know the Rats have got their fraud on (as the kids say).
Register DEM and vote for Sharpton in the DEM primaries. That should shove a finger into a very uncomfortable place in the DEM party. Let's see how they handle a good show for Al in the primaries.
The Rats are about to get a lesson in "what comes around goes around". Remember how they went to polls in droves for McCain? It's time to return the favor.