It could be that they faced some kind of difficulty or disappointment. Maybe the child didn't get what he wanted, or the mom had a bad day at work and it affected them both.
Perhaps there was a sad event in their lives, like the loss of a pet or a move to a new place that made them feel down.
Maybe he lost his favorite toy or didn't do well in a game.
Maybe he lost his favorite toy or got into a fight with his friend.
There are various reasons. Maybe his pet ran away, or he was bullied. It could also be that he saw something really sad happen to someone else and that made him feel bad.
Maybe he lost his favorite toy or didn't do well in a game.
The cartoon black child could be sad because he didn't get good grades at school or had a fight with a friend. There could be many reasons.
It could be that the child had an argument with a sibling or parent before getting in the car and is still upset. Or perhaps they're just not feeling well and the car ride isn't helping.
Maybe the child is sad because of something that happened in the story. And not being white could just be a random design choice.
Maybe he lost his favorite toy or got into a fight with a friend.
Maybe they had a fight or lost something precious to them.
Maybe he lost his favorite toy or had a fight with his friend.