This might not be so relevant in south-east England but here goes...
Long experience of automated calls with an 'important public announcement' turning out to be about how to write off my non-existent debt by taking out another loan or some other rubbish advertising something or other mean that I now hang up every time I hear a robot voice on the phone. If there was an actual emergency message, I would completely miss the warning. Examples I can think of include an explosion at a power station or chemical processing plant necessitating everyone staying indoors (happened around here a few years ago), madman with machine gun roaming the streets (ok, unlikely), civil unrest (very likely where I live when there's a football game on!) etc. Thinking back to the bushfires in Australia last year, isn't there an automated telephone warning system if your community is under threat and residents need to leave? What would happen if people got used to automated calls and so just hung up?
So, AIBU to think that such automated calls should be made illegal so that should a real emergency ever occur, warnings don't get ignored?