Well if there was nothing between your car and the radio station, you wouldn't have a problem either.
Edit: It seems the satellites they are using to communicate are on the Earth's surface, so there is atmosphere in the way. But still the dishes are pretty big compared to your car antenna.
Surely over that distance, there is plenty of loose rock etc flying through its path that could create noise in the data? I mean there are pretty big meteorites out there.
True. Surely it's less dense than buildings, trees and the fact that 50k watts doesn't mean much when you don't have line of sight (Earth curvature) which is, even with the some of the highest towers is only 63 miles.
Would be interesting to do the math on the density comparison though.
I don't know much about sending data over distance I just thought its crazy to need such low amount of power to do so from where it is :P