As hinted at in the article this is how the US justice system works.
Plea bargains all round, especially from the poor.
It's quite simple, risk a trial with terrible defense, crippling bills and debt and a potential 99 year sentence, or do what almost everyone does and simply plead guilty in exchange for 10 years eligible for parole at some point before that.
Saves a whole load of time, money and effort on behalf of the state.