The thing is, there's already an established alert level for Amber alerts coded into phones. For one reason or another, the Canadian officials that decided not to use this alert level when implementing the Canadian Amber alert system,, and instead use the Presidential level alert. Presidential level alerts are meant to only be sent out when there is clear and immediate threat to the phone user, i.e. terrorist attack, missile strike, etc. It's meant as a "pay attention immediately because your life is in danger" level alert.

I have absolutely nothing against sending out amber alerts and ensuring that people who are already up and about getting a message notifying them. However, using the presidential level alert for amber alerts is just overkill. There's no reason to blare a loud alarm for an Amber alert, and absolutely no reason to send a follow up blaring alarm when it ends.