The fact that this is an issue is scary. A notch filter isn't particularly expensive, doesn't have a large effect on the received strength, and is basic good design on any RF component that needs to isolate a signal in a specific band, so this was simply for profit motives.
For those who are not terribly familiar with radio frequencies this is analogous to using Security By Obscurity. The designer just decided to gamble that nothing would happen to transmit in a band that the system would catch in a pattern that the receiver would interpret as a valid signal.