It is quite localized.

There used to be many small companies. Tested to be good response time and courteous. One by one they are falling into the big company, such as ADT. Because it is big with many customers, the response time is quite slow and/or missing.

For a real thief they will go to several high value area in 3 min and be gone before police comes. Hence any latency in reporting is bad service.

Of course it is always better than not having one to monitor, so actually the posted sign is more powerful than the actual monitoring.