Of course I am being a bit tongue in cheek here, but all those
folks respond no matter how they are alerted to the emergency.

And if you ever run into one of those Sheriffs responsible for
overseeing a search who is in the office purely for political
reasons and doesn't want to spend any money on a search, you
will be glad you have friends and family to push for every
resource, including all those agencies mentioned.

Would you want the ones running the Katrina response looking
for your injured and lost family member?

No one is going to look out for you and your family's welfare
like you will.

A PLB is a one trick pony.