There are common factors that conspire against younger voters.
1) Younger voters tend to have to work harder to make ends meet, due to less job experience, and statistically lower salaries than their older counterparts.
2) This means younger voters tend to lack time as a resource, which is necessary to properly approach the democratic machinery, since the voter must have time to be able to self-inform, AND, have time resources available to plan and interact with that machinery, in terms of actually arranging going to the polling center to vote. Remember, this includes such things as finding childcare, so that the statistically likely to be present children are cared for while the parent goes to the polling center.
This is in stark contrast to the often inimical boomer demographic, which is often retired-- and thus has CONSIDERABLE time resources, and often significant savings/investments upon which they support themselves, and typically have long-grown-up children that they do not need to care for. In fact, they may even be directly chauffeured directly to the polling place. (This is especially true for retirees in assisted living centers or nursing homes.)
In short, while there are many young voters, you are overlooking the very real costs to opportunity that those young voters are facing, compared to their older counterparts that frequently work against their interests.
If it weren't for the fact that doing so is illegal, it is quite likely that these opportunity costs would be purposefully leveraged to prevent young voters from voting at all, by denying them time off from work to accomplish said voting. AS-IS, the system simply carpet-bombs older voters, who have a much higher turnout (Due to greater opportunity), gets them all riled up and infuriated about %POLICY%, and generally plays the older voters for suckers against the younger ones, to satiate various business and political interests. (See also, PACs, and Thinktanks.)
This COULD be addressed by increasing the polling hours or polling windows for voting, but that would increase the administrative costs of government considerably, and so it will never happen. (THAT, and also, it would make the PAC and Thinktank groups very upset.)