The parents want to be their childrens' best friends, and so fail to teach them respect for authority and discipline.
If you aren't willing to do anything about your child's bad behavior, it is best to blame it on everyone else. Too many parents use "hope" as a parenting tool i.e. I hope he stops doing that. Confrontation is bad in their eyes because they don't have the will to win. I find that especially true of single moms raising boys. Probably because I don't know any single dads.