It can't have an end stop.
Any application for such a switch has to have some datum point, and none is provided by the switch. It is designed for car AV equipment, and a car cannot leave power on a switch all the time or the battery would go flat.
If a car stereo had been turned up a bit loud, and then the car shut down, and then someone turned the volume to the counterclockwise stop, the stereo couldn't have noticed that the knob was turned. Then when the car it turned on, the user would have no way of turning the volume down, without turning it up all the way, which could be very loud, to set the top end of the volume range.
That simply doesn't happen. There is no stop. If the knob is turned with the car off, nothing happens, and the lack of at stop means that the user can always turn the volume down. The ends are provided by the zero to max range of the electronics.