I’ve not seen more than the first episode of Anne With an E, but I definitely had the impression they were making explicit what was mostly subtext in the first novel. And ‘orphans’ weren’t adopted because someone wanted a child of their own, and the adopter was felt to be the best fit for that child — they were free child labour.
It’s not clear whether the two previous families Anne lived with actually adopted her and handed her back when they didn’t need her labour, or whether the orphanage just saved money by handing out kids for extended periods to people who would feed them in exchange for work.
But the thing is that Matthew abd Marilla are doing this too. They send off by word of mouth for a third party to pick them out a strong boy because they need labour on the farm, because Matthew is getting older. Clearly they wouldn’t have been abusive, they plan to send him to school and to eventually leave him the farm if he’s satisfactory, but they’re not adopting a child to love, but free labour. A sort of servant, who will work for his keep. That’s why when Anne arrives, Marilla doesn’t know where to put her to sleep, because she’d prepared a bed in the ‘kitchen chamber’ for the boy, because he was not going to be one of the family, but ‘staff’.
Anne’s backstory is pretty ugly.