The cartoonist doesn't seem to realize that corporations buy candidates for both parties and sponsor elections in order to reduce their taxes and for many other self-serving reasons. They sponsor elections to fool people into thinking that they have real choices and are participating in some kind of democracy. This is much more cost effective than using a police state apparatus to enforce their will.
But, just in case people wise up, they have constructed a police state (the Patriot Acts, 24/7 surveillance, militarized police forces, etc) that is ready to quash any resistance. You see, they don't take any chances to allow for change. The worst nightmare they have is that the people will kill the goose that lays their golden eggs of profits and power--capitalism!