I am aware that you were making an like-to-like comparison with your selection of those Muni and CTA graphics. However, for those who don't know, Muni is more than just the light rail lines shown in that picture.

Here's a complete system map: http://transit.511.org/static/providers/maps/SF_122220102111...

The equivalent CTA system maps seem to show just as much bus coverage as Muni's bus coverage. (Now, how many of those bus lines keep running after 23:00 is another question, entirely.)