Economic status vs. Single parents

I've continued to think about comparing low economic status and single parenting and how those affect a child. Obviously, living with a single parent presents can create many disadvantages for a child, economically and psychologically. Interestingly, teenagers actually have a harder time adjusting to divorce than younger kids due to an inability to open up and discuss their feelings: thus, divorce that occurs during adolescence can have a lasting effect. (http://www.psychpage.com/family/divorce/childrenadjust.html) However, I'd still maintain that the disadvantages faced by the children of single parents are no as bad as the disadvantages faced by poor families.
First of all, it's important to note that most single parents are usually lower income. Many single parents (usually mothers) were never married (as opposed to divorced) and have a child due to an unplanned pregnancy. This can make it difficult to distinguish between what issues are caused by lack of time (because there's only one adult) or lack of money (because there's only one source of income). There's a lot of crossover between these two categories, and that's where the crux of my thinking comes in: many of the disadvantages that a child faces by only having one parent disappear if the parent is economically successful. And conversely, many of the same disadvantages a child of a single parent usually has appear when a child has both parents present if they are not economically successful.
For example, a child from a lower income bracket will almost never perform as well in school as a child from a higher income bracket. This can be attributed to many factors; mostly that a poorer child has more important things to worry about than grades, such as food and safety (see Maslow's Hierarchy). In addition, a poorer child has fewer opportunities. After all, college costs money, and so do many extracurricular activities.
A poorer child's increased risk of going to jail does seem to be connected to only having one parent. One of the major reasons a teenager starts committing crimes is the combination of an abundance of free time combined with a lack of supervision. Still, this does not account for crimes of desperation that occur from lack of funds.
I think an important thing to do is separate divorced parents from parents who have never been married because children with divorced parents come from all economic backgrounds where as children with a single parent usually come from a poorer background, and thus are at much higher risk to underperform in school or even end up in jail.
I could go on, but I'm curious as to what you guys have to say.