A few questions for you :)

[PieEater]

dont know about the 1000's but most number plate lights are just from the tail/brake light
if you have a look underneath it will be clear and can see the bulbs/reflector

Exactly, the tail light has a clear lens underneath that directs light from the bulbs onto the number plate, when the brake lights come on more light is directed through this clear lens as well as through the red portion of the light, it's just the way it is designed.