I think it for many reasons. Some are too lazy to register. Some don't care what the goverment does. and Some do not know when to vote. I tell ladies that we have been fight for our right to vote not for 80 years as some beleve but since before we were even a country in our own right. My example of this is Abigail Adams in her March 31, 1776
letter to her Husband and I quote "I desire you would remember the ladies and be more generous and favorable to them than your ancestors. If particular care and attention is not paid to the ladies, we are determined to foment a rebellion, and will not hold ourselves bound by any laws in which we have no voice or representation. " John Adams did laugh at this but then had change the word men to people in the U.S. constitution.

 So that my topic of the day I hope you learn something new.