She didn't know so she took the child and fled before she could be stopped. She KNEW there was a chance that he was Dad. She didn't care. It was about what SHE wanted. And SHE wanted someone else's child.
But any person in her situation would know for sure that there IS a biological father who might or might not know about the baby.
Perhaps you are arguing for adoption only when there is a clearly identfiied and proven father who has consented to the adoption.