Earlier quoted context omitted.
To get notifications about an alert in a given area?
Considering that EAS's are handled at a hardware level and a public subscription API sounds ripe for a targeted DDoS attack for a pull model and bound to fail for a push scenario, I think radio, TV (OTA & cable), and Cell/Mobile are sufficient to reach the vast majority of people. Really only people who completely eschew technology would be left out since news orgs will be quick to update their web sites and forward…
I work on digital displays and I would like to help spread awareness when alerts occur. It is an incredibly complex process, made for big telecommunication companies.
A public API could save lives. You can't even ask them to send you a SMS on Twillio and make an API yourself. They send it through telecommunication networks, not by sending SMS to everybody.