Why would they go to school then, if they have personal teaching AIs?
There are loads of reasons. For laboratories or practical learning. They also need social interaction with their peers. While they can study different things, they can talk to one another during their breaks. It is also possible that initially, the AI teachers are only available in schools. In first world countries, schools have also shifted a bit to also be an extended day care. The children are dropped off there while parents work, and they can stay there until the parents come and pick them up.