This is actually a really great analogy for not the reason you're thinking, because of the fairly common incidence of car accidents. Sure, the surface of the e

This is actually a really great analogy for not the reason you're thinking, because of the fairly common incidence of car accidents. Sure, the surface of the earth is not crowded due to the volume of cars. But that doesn't mean that car traffic is trivially easy to solve or travel is automagically safe. Space flight safety should mirror (or be better than) air travel safety (in accidents per mile terms); if space flight becomes more like cars, then space flight is probably screwed.