TLDR; Technology changes, so should emergency alerts. Think ahead to 2029.
The long story:
Technology changes over the decades. Emergency alerts have changed over the decades. If you think all the other ways are sufficient, remember how long it took to create all those other ways. And how much industry fought
all those other ways at every step.
The U.S. timeline (other countries have state-owned broadcasters, and different timelines):
1950s - AM radio and civil defense sirens
1960s - FM radio and TV broadcasts were included in EBS
1970s - Weather alerts and NOAA weather radio
1990s - Cable TV (not satellite) was included in EAS.
2000s - Satellite TV was added to national EAS alerts, i.e. there has never been a national EAS alert. But Satellite TV do not get state or local weather alerts on most channels.
2012 - Mobile phones were included with WEA expansion
If streaming is how the public gets their information and entertainment now, that should also be how they can get emergency alerts.
Almost no one under the age of 30 has a working AM radio in their homes or apartments anymore. Few people listen to FM radio outside of their cars, and "cord-cutting" means fewer people get local and weather alerts watching entertainment programs on cable TV. Cities have been eliminating outdoor warning sirens due to budget cuts since the 1990s (i.e. end of the Cold War, and no more FEMA funds for sirens).
Wireless Emergency Alerts (WEA), i.e., mobile phone alerts, are less than 10 years old. And mostly on the high-end expensive cell phones and the most expensive carriers. People on NANOG may use mostly expensive smartphones, but not everyone can afford smartphones. Only about 100 carriers, including AT&T, Sprint, T-Mobile and Verizon, carrier have WEA working. In some U.S. territories and rural areas, no cellular providers have WEA working. The largest cellular carrier in Alaska only activated WEA in the last 6 months. Puerto Rico's largest cellular carrier activated WEA just last month.
The mobile cell phone industry fought Wireless Emergency Alerts for over a decade, from the 1990s until 2012 when it was implemented. Of course, now the wireless industry claims it was all their idea. Both are true. The cellular industry engineers made it happen, at the same time the cellular industry lobbyists were fighting it.
If emergency alerts didn't change with the technology, it would still be only AM radios. It usually takes at least a decade after technology changes to make changes to the emergency alert parts of those systems.
It took more than 10 years after the 9/11/2001 attacks and Hurricane Katrina, which were the motivating factors for government, to get WEA working.
If you think WEA is sufficient, just remember how long it takes to change. In 2029, what communication technology will be the dominant way people get entertainment and information?
As I've said before, I think emergency alerts should be part of the platform, not the add on service. Netflix and Hulu are the wrong layer for emergency alerts. Emergency alerts should be part of the Smart TV and Smart Speaker operating system platforms, i.e., at the Amazon Alexa, Google Assistant, Apple Siri, etc. level.
If you are streaming Netflix or Hulu on your mobile cell phone, the cell phone OS should be responsible for handling local emergency alerts. If you are streaming Netflix or Hulu on your Smart TV, the Smart TV OS should be responsible for handling local emergency alerts. If you are streaming Netflix or Hulu on your Smart Speakers (ok, you can't but lets say streaming an Audible book), your Smart Speaker OS should be responsible for local emergency alerts. Your alerting opt-outs, geo-targeting, and other preferences shouldn't need to change depending on which App you are using on the platform.
NOAA Weather Wire and FEMA IPAWS emergency alerts, which are the alert aggregation points for most U.S. alerting systems, include geographic alert polygons within 0.1 mile. Emergency alerts can be very localized. Although training for local government officials is skimped, underfunded, ignored, etc.; so many still send alerts for entire jurisdictions, such as statewide in the U.S. or province-wide in Canada instead of geo-targeting specific areas.
Cell phones have ATIS and 3GPP standard for emergency alerts. Cable set-top boxes have SCTE standards for emergency alerts. TVs with antennas have ATSC standards for emergency alerts. Analog radio still relies on broadcasters transmitting emergency alerts, i.e. that triple burst of modem noise.
ISPs are also part of that, since ISPs know where their subscribers are geographically located.
And yes, I'm a big believer in personal choice. Individual alert
opt-outs and geo-targeting is critical. I think Canada (and New Zealand, and some other countries) are making a mistake by using the "mandatory" alert setting for all alerts. I also believe emergency alerts should be accessible to everyone, not just rich people with the most expensive smart phones and carriers.