Some reasons why poor people don't vote as much as wealthy people:
Because there really isn't much difference between voting for one prep school grad or another.
Because the discussed issues aren't really significant enough. Sure, there a talk of "more jobs" but the poor know that they won't see a whiff of it.
Because felons aren't allowed to vote. And because a percentage of the poor are in jail or prison, whether misdemeanors or felonies. They don't get to vote, either.
Because working and cooking for one's family and helping the kids with homework seems like a better use of time.
Because many of the issues are esoteric and require education as well as the ability to be functionally literate. Almost no one wants to vote on what they see on the TV or hear on the radio.
Because when the poor do vote, and their candidate wins, nothing changes. So why vote next time?