I don't understand this law, I believe it is for thr parent wanting to keep the kid and not the child's decision.

The child never gets to decide in any US state. They may in court testify what they want, but the court does not have to do that. The court will always look at what they believe is best for the child.

Yes it IS like that in all US states. A minor does not get to choose. Custody has to be awarded by a court. The court is charged with consideration of the best interests of the child.

Some states do have guidelines for the court as to how much weight to put on the child's preference depending on age. But it is still the decision of the court.

There is good reason for the law. Its not so the custodial parent can keep the child, its so the child can be protected from making a bad decision.

For example. Mom is very strict and won't allow her 14 yr old daughter to date. Dad is more lackadaisical and doesn't care. So the daughter wants to move in with dad, so she can date her pot smoking, 18 yr old boyfriend. This may be an extreme example but it illustrates the point.

We have another thread active where a 16 yr old wants to move in with her mom after her aunt and uncle kept her for 12 years by lying that they had legal guardianship. In this case, the court is highly likely to affirm the child's wishes.

The point here is that the court makes the decision based on the circumstances and what the court feels is the best interest of the child.