There is a light in the fridge and not in the freezer due to climate control. The light would freeze in the freezer. However, the fridge is not cold enough to do this. The light gives off heat which is fine for the fridge.
As well, we are more apt to dig in the fridge for a late night snack than the freezer... unless it is for ice cream, yum!
But I do believe it just depends on the model.
Most modern freezers accommodation a light.
Hope this helped