You can get the same with burglar alarms
The one I was looking at yesterday says it can be set and unset by SMS.
Naturally, there is a user password which has to be part of the SMS. But it is just a simple user-defined string of digits and it is the same string of digits every time. So anybody who can capture SMS (which must include some of the staff at the telcos operating the sending and receiving devices, and possibly others with the right eavesdropping equipment) knows exactly how to disable your alarm.
Probably not a sensible feature to enable until somebody comes up with a reliable encrypted SMS replacement.