People don't vote because they don't have faith in the system because it's so bloated and non-efficient. At least a lot of the people I know who don't vote feel that way. Couple this with not wanting to elect any
of the people running and you have a reason for low voter turn-out.
I wonder how the voter numbers would do if there was a new option added to the polls; i.e. if enough people voted "none of the above" then the election would be held again and neither of the previous cantidates could run in it.
Might be interesting.
Of course the question then arrises of how would things be done if elections had to keep being done over and over...