The reflectors do not need any power source, nor interior lights, nor to be activated by the driver since their operation is completely passive.
The reason is that the material with which they are made reflects light with great intensity. In this way, it is enough to mount the reflectors on the motorcycle so that they shine with the lights of the vehicle behind.
The colors of the reflector determine the place where they have to be placed: red for the rear of the motorcycle and yellow on the sides, the latter are optional.