Earlier quoted context omitted.
A 911 button exists! The people that have them use them often... Google: 911 system for elderly
It's not only about elderly. Imagine you have a stroke, or your hands are full of blood, or you fall and brake your hands ...then you cannot use your touch screen smartphone and/or speak comprehensible words! In such emergency situations a text-to-speech would save life's. You may be able to press a physical button or the G-sensor detects the accident and reacts automatically.
>or the G-sensor detects the accident and reacts automatically
Just don't ever drop your phone.