A person legally responsible for the support of a child under the age of eighteen years who is not subject to any subsisting court order for the support of the child and who fails to provide support, subsistence, education, or other necessary care for the child, regardless of whether the child is not or was not in destitute circumstances, is liable for the reasonable value of physical and custodial care or support which has been furnished to the child by any person, institution, agency, or human service zone. Any payment of public assistance money made to or for the benefit of any dependent child creates a presumption that such payment equals the reasonable value of physical and custodial care or support.