My mother-in-law could have been a poster girl for the "if you fall" ads. She tripped and broke a leg. Unable to reach the phone, she lay on the floor for almost three days in freezing weather.
As a result of this incident she got one of the monitored services and on more than one occasion it proved to be well worth every penny of the monitoring fee. The complete system consisted of much more than a simple alert button. The service included a two way audio monitor so that when the alarm was triggered the service technician could activate a speaker system in the house and carry on a two-way conversation with my mother-in-law to determine the exact nature of the problem. It was sensitive enough that she could be heard even if she fell or needed help on the exterior porch. If my mother-in-law was for any reason unable to answer the technician could listen and see if anything could be heard that would give a clue as to the nature of the emergency.
The procedure then was to immediately dispatch the proper aid, fire department, EMS, or police and only then notify the family members. The family notification included a tiered notification structure beginning with the family member in the nearest vicinity and then those in more remote locations.
A system such as you were describing has too many potential points of failure. The family member is away from their phone, they left their cell phone on the desk and went down the hall to another room, they were in the car and passing through a dead zone, the battery in the cell phone failed, they were on another call, etc. The monitoring service guarantees the dispatch of appropriate help in the shortest possible time and sometimes minutes can mean the difference in life or death.
When you compare the cost of the monitored service to specialized "day care centers", in home assistants, or moving to a monitored facility, the cost of a monitored in home system is negligible.
