Cost to Society
Humans evolved in families and tribes in order to survive as a species however this is no longer necessary in modern living. Financial incentives by governments and a legal system that effectively rewards parents and others who breakup families by alienating children has contributed to a large number of children who are not raised by both parents. Most of these are raised without their father however many are also raised without their mother.
In a case where a child is raised by only one parent and the child has some relationship with the other parent the child has some leverage to be able to threaten to want more time with the other parent or run away to live with the other parent. This undermines the custodial parent's authority to discipline the child. In many cases due to our family law system which rewards rights and money to the custodial parent each parent will be bidding for as much of the child's time they can have with them. Fathers are typically the marginalised parents and the phrase 'Disneyland Dad' was created to recognise this reality.
With our adversarial family law system, the custodial parent is encouraged to denigrate the other parent to the child. For example:
'It is a sad fact in the family law jurisdiction that a determination which is most consistent with the best interests of the children can appear to reward bad behaviour on the part of one parent and work in apparent injustice for the well motivated and best performing parent.' Bennett J (FamCA1251  paragraph 77)
In a classic case of parental alienation the parent child roles are inverted so the child is raised without normal parental discipline. These children are cult like followers of the Alienator so in many cases they come across to outside people as children very well behaved.
The data is very clear that children who are not raised by both biological parents inflict higher costs on society in various ways. The damage caused has on the whole been poorly quantified by academic and government studies in many western countries due to an unwillingness of government to quantify the problems of liberal divorce laws and single parenting.
So much sadness is caused to so many people who have lost loved ones from the loss of life induced by our family law system. Considerable sadness and misery is inflicted on families and friends who suffer an acrimonious divorce. Additional misery from adverse mental and medical health problems is generated by the family law system.
Children who are raised in fatherless homes represent 70 % of children in juvenile detention centres, 75 % of adolescent patients in substance abuse centres and 85 % of rapists motivated by displaced anger so the amount of additional crime generated by our family law system is considerable. Almost all the mass shooters in schools in the US came from homes where the parents were either divorced or alienated.
Parkland Florida School Shooter Nicholas Cruz
The data indicates children who are not raised by both parents achieve somewhat lower educational attainment which could be expected to have an affect on our national productivity. Many parents spend inordinate amounts of time over many years litigating which wastes time that they could spend caring for their children or producing goods and services for the nation. The higher rates of substance abuse for the children who are not raised by both parents could be expected to impact on employment productivity.
Going to court costs parents and taxpayers considerable amounts of money. Other government departments that deal with the direct costs of family breakdown include child protection agencies, police and magistrates courts. Indirect costs include theft, the cost of cleaning graffiti and extra health costs from adverse childhood experiences. Our education system has additional costs and reduced efficiency caused by troublesome children who are raised by single parents.