Trut you're sharp enough to figure that out. In many cases latch key kids have no parent in the home most of the time bc the single parent responsible is always at work. The problem IMO isn't money, its leadership or lack thereof. My dad came up dirt floor poor and has 2 masters degrees. School books are free, so is the lunch and supplies if you are poor. Money is not an excuse to make bad grades. Its either a lack of intelligence, or a lack of discipline. Most of the time its the latter.
You stated that mom not being around because she is working two part-time, minimum wage jobs is a problem; you stated this after saying that education has nothing to do with economics. I found that odd.
Here, again, you have stated that there is a lack of leadership in the lives of latchkey kids; these kids are latchkey kids because their parents are working. So, again, economics is playing a role (how substantial that role is, I will not venture to estimate) in academics.
The majority (there will always be exceptions) of children lack the drive and initiative to be self-starters and self-discipliners; parents ought to fill this void and instill these qualities in their children as their children mature. Parents that are constantly working have a harder time doing so.
Your father sounds like an exception; however, your father also might have benefited (I do not know, though) from having a stay-at-home mom in the house who, while they were poor, was there to instill discipline and motivation.
I was fortunate enough that my Mom worked nights until my older sister was in 5th Grade; then she worked days. She would still fix dinner and took an interest in our lives and in our schoolwork; however, it was my older sister who disciplined my brother and me and forced us to do our homework when we got home from school. This was possible because my Mom had deeply instilled those values in her; she in turn instilled them in both my brother and me.
The fact that parents have such an influence on their children's education, combined with the fact that many parents work (and work a lot), leads me to believe that public schools (if we are actually asking the public education system to educate our children) should be boarding schools.