They are several reasons at play as to why poor people don't vote.
Voter ID laws and registering to vote
The Government Accountability Office found in this report, that in most state it costs between $5 - $60 to obtain a vote ID, alternate ID like a passport or driving license also cost money to obtain, and people who don't travel or don't drive may not have needed either before. This may not seem like a huge amount of money but when you're on the breadline every dollar counts.
Also another factor is that poorer people are more likely to move home than wealthier people, and that moving home can jeopardize voter eligibility as you have another layer of red tape and paperwork before you can get to the polling station, an MIT study estimated that 1.2 million votes were lost in 2012 due to registration problems alone.
Elections are held on working days
A lot of poor people are paid by the hour, and if the election is being held on a working day (like in America) you simply can't afford to take the day off. In the 2014 US mid-term elections, a report commissioned by the Pew Research CenterCentre found that 35% of people who didn't vote did so because of scheduling conflicts with work/school. Countries where voting is held on a week-end or public holiday like Australia, Brazil, France, Germany, and Italy typically have higher voter turnouts.
A sub-category of this is long lines: in 2016, people sometimes had to wait for hours to cast their ballot. For someone who is losing money for every minute they spend in a line to cast their ballot, having to spend several hours is unappealing at best.
Education, education and education (and apathy)
Poor people don't have the time to read thousands of pages of news/policies and they don't spend their luncheon reading the Economist. As your article says, policies tend to be tailored towards wealthier constituents, so poorer voters may have difficulty understanding some of the more complex or technical terms used in the political discourse. Another article which claims this is here; poor people don't feel represented so they don't vote. A very blatant example of this was the 2016 Presidential Election where both the major candidates of political parties (Hillary Clinton and Donald Trump) were multi-millionaires/billionaires who had extremely good educations (Yale/Wharton School of Business); these education institutions are often inaccessible to the poor. In fact, almost every single president of the US has at least been some form of millionaire.