In many countries the authority and capability to send alerts is relatively decentralized and/or they require people to be inserted in the decision loop. Things are this way for policy and jurisdictional reasons. To change it you'd need to redesign the bureaucracy and authority, including many parts that have nothing to do with emergency services. Those changes are not going to happen.

Under these constraints it is effectively impossible to send automated alerts at scale with low latency as demonstrated here. A private app does not operate under such constraints.