Weird Case

Sometimes the State just won't let go. Crazy story in today's Star-Telegram. Female gay couple have a son. While one parent was unlocking the front door the other parent remained behind the wheel of the car in the driveway. Son is killed in driveway when their vehicle "lurches forward." Alcohol tests reveal alcohol concentration of .06 (below the legal limit of .08). Prosecutors want to prosecute. The non-defendant parent does not want them to. They do anyway. Yesterday, right before jury selection, a plea bargain is struck for three years in prison (max was 20). But I wonder why they wouldn't offer probation in a case like that?