I had a political science teacher who had a theory about this. During election years, candidates on both sides don't want to waste their campaigns by trying to cater to the 18-35 white people, who have the lowest voting percentages. They take care of this group by offering very simple things such as lower gas prices to lessen their drive to want to vote, letting the candidates focus their attention on campaigning for the elderly and minority groups. He said that this was why Clinton was so popular when it came time for elections. He was one of the first to actually pander to the young non voters.