Whether you're treating yourself to a nightcap of chilled Chardonnay, or sneaking down to get a midnight snack, it will always greet you like a beacon in the veil of the night: the little trusty light in the fridge. Your personal savior. Sadly that is not the case if you go for, say, a midnight ice cream sandwich. So why isn't there a light in the freezer, but always a light in the refrigerator?
The reason is relativity and cost-efficiency of course. Money not only makes the world go round, but it also makes your freezer dark and your fridge lit. On its own, a set of a tiny LED light and some wiring isn't that expensive. But in relation to the entire cost of manufacturing the fridge, it becomes a considerable expense to the manufacturer. That explains why back in the day there wasn't any lighting.
This custom stuck for both reasons: the power of habit (both on the consumer side and the manufacturer), and again, cost-efficiency. To this day it remains beneficial for manufacturers to skip the light in the freezer. As for sales, marketing the freezer light as "additional" renders it a luxury, making it more likely that you'll pay extra just for a little light bulb and a switch!
There is another explanation, though it is not as likely as the latter. There are claims that ice buildup can cause the light to dim over time, and since the freezer is packed more tightly than the fridge, we can skip a freezer light altogether. What's more, you usually use the freezer for things that require further preparation, so chances are the kitchen light is already on.
Are you satisfied with these explanations? Let us know!