I appreciate Grant's point that life can feel really unfair to children (and it really can be unfair sometimes) and it can feel frustrating to be out of control. But most of the examples here aren't really unfair, and I think Grant missed a crucial opportunity to teach about fairness not as "everyone gets the same exact thing" but as "everyone gets what they need." For example, the difference in size between the father's cider and the kid's cider are proportionate to their sizes, so I would call that fair.
I also think he missed an opportunity to teach about WHY adults are most often in control of the decisions. Instead of just saying "Pablo, I'm in charge because I'm your dad," the father could have explained how parents have to make choices to keep their kids healthy and safe, and they get to do so because they've had more life experience, but gradually, they let their kids make their own decisions.
So I get that this book is really meant to be more fun & funny than seriously help them with the concept of fairness, but I think it could have done both if Grant had thought through the messaging a bit more carefully. I think it's important that we explain our decisions to kids more, and then they will have an easier time accepting our rules.