Think about it. Why is there a light inside the refrigerator and when the freezer opens, isn’t it? This question was asked to economist Robert Frank by one of his former students. The answer is very interesting and, according to the economist, it is a rather classic example of the cost-benefit principle.
The cost of putting a light inside a freezer, exceeds the benefits. The reason is soon said: consumers use the light of their refrigerator practically always and is therefore a valuable feature. Manufacturers can therefore justify the cost of installing those lights much more easily than they can do with the freezer lights.
The freezer is not opened at the same frequency as the refrigerator. Unlike the fridge door, you usually don’t stay for a few minutes to watch what to eat when you open the freezer. It is also worth considering that it would make no sense to put a light in the freezer, because simply the accumulation of ice would hide it very soon.
Today there are automatic de-icing freezers, but most likely when they arrived on the market it was already “tradition” that there was no light inside the freezer. Of course, no consumer has ever actually asked for it… even if today the most technological models have one.