Thanx. Never knew that. I guess every diplomat would be dropping kids when they come here.
It is not just that.
Let's say a diplomat has a son born in a country where they have the draft. Without that protection they would be able to try to take him when he turned 18. Or 16 some places.
It can get sticky so for simplicity children of diplomats are considered legally only citizens of what ever country they are from.
Not just a US rule. It is a standard diplomatic agreement.