As a point of clarification, Amber Alerts are a part of State EAS plans, and it's primary focus is that of broadcasters (radio, TV and Cable). There are some active highway signs that are part of the system, and police are notified of an alert, but it is directly related to an EAS alert on broadcast entities.
Every state has an EAS Plan:
and Amber Alerts are a part of that plan:
The State EAS plans are reviewed by the FCC. The Amber Alert Criteria vary state by state, but here is the criteria for Maryland. I am sure Nevada's is similar:
Maryland AMBER Plan Criteria
The following criteria are utilized to determine if an Amber Alert should be issued for the State of Maryland:
1. Law enforcement confirms a child has been abducted.
2. The child is under the age of 18.
3. Law enforcement believes the circumstances surrounding the abduction indicate that the child is in danger of serious bodily harm or death.
4. There is enough descriptive information about the child, abductor, and/or suspect's vehicle to believe an immediate broadcast alert will help.
5. The child is believed to still be in the broadcast area.
6. The child's name and other critical elements have been entered into NCIC by police.
ONLY A LAW ENFORCEMENT AGENCY CAN REQUEST AN ACTIVATION OF THE AMBER ALERT SYSTEM THROUGH THE MARYLAND STATE POLICE.
It sounds to me, that while this is being referred to as an "Amber Alert," it was really a reaction of local authorities to a report of a missing child. I am not in any way defending or criticizing these actions, simply stating that calling it an "Amber Alert" is a misnomer.