So you’d rather they sent a time sensitive alert by text. Not only does that mean they’d need to know everyone’s phone number but that if anyone had a phone off and then switched it on a few days later, they’d get an alert that’s no longer relevant.
It also means they couldn’t send localised alerts which is the point of this. The alert can be down to a single cell.
Good thinking. Not.
This.
Also, the emergency transmit band is not 3g/4g/5g but an independent part of the spectrum with different MCS rates to maximize coverage. You can get them even when you have zero bars of reception., but are still just inside the cell range