This is true. It beeps when unarmed. She could be mistaken as to whether it is "armed" or not. If it's "armed" during the day, you do have to keep punching in the code every time you open a door or window...which is a nuisance, unless you are really in fear that compensates for the inconvenience.
With a small child and a bunch of housekeepers, I presume most people wont' keep it "armed" during the day. Otherwise, police would be showing up day in and day out.