While this incident might be unusual to any normal human being, the (possible) attitude behind it isn't. When I was working through college at a deli, one of my co-workers was in a similar situation. She was 24 and had four neglected children.
Every day the rest of us had to listen to her complain that she was always out of money and had no free time, yet nearly every other day she came in wearing a new wig or hair extension, and ALWAYS made sure she had cigarettes (among other substances). Once, she didn't show up, and while we were trying to find her, her six or seven year-old son called up looking for his "mommy". When I heard this sad plea over the line my jaw dropped, and pity overwhelmed me.
Needless to say, this type of thing was routine for her. When she left she was also pregnant.
Because of this, I was not shocked when I heard of Taragee Maynor. I'm not going to claim to know why it happened, but my first thought was just complete, braindead negligence.