so the chıld ıs not the fathers but someone elses.
Therefore how would you say "The chılds father has to take him to school"
I guess çocuk and baba swap round to become "çocuğun babasını"
I feel like most Turks would avoid that sentence is ambiguous (does "him" refer to the child or to the father...who knows).
However, the sentence would be "çocuğun babası onu okula götürmeli." No reason to put the accusative on "babası"
In this sentence, "onu" is replaced with "çocuğu". Thanks to that, the sentence became shorter.
Why is ''The child's father has to take him to school'' incorrect?
Simply because that what the sentence says. çocuğu is an object, not a possessor.
Why not 'Their father'? It works both as a gender-neutral pronoun or as a plural, as far as I can see
Its/his/her father = babası
Their father = babaları
And there is no masculine or feminen thing in Turkish. Turkish treat both genders equally ;)