If you’re trying to stealthily swipe a midnight snack from the refrigerator, you’re in luck—the built-in light makes it easy to see what you’re doing. If your treat of choice is frozen, however, you’ll probably have to whip out your smartphone flashlight or go by feel alone: Most freezers lack their own light source.

As economist Robert Frank explained in a blog post for PBS NewsHour, this is a pretty classic example of the cost-benefit principle, which basically means that the cost of something shouldn’t be more than its benefit to consumers. Since consumers use the light in their refrigerator quite often, and therefore consider it a valuable feature, manufacturers can justify the cost of installing those lights much more easily than they can with freezer lights.

As for why consumers don’t value freezer lights very highly, the most popular explanation is that we simply don’t open our freezers as often as we do our fridges. And when you do open your freezer, you may be less likely to stand there for a few minutes surveying the options.

According to Today I Found Out, another theory is that it wasn’t worth installing a freezer light back when it would’ve likely ended up concealed by ice accumulation. And by the time self-defrosting freezers hit the market, consumers had already gotten used to not having freezer lights.

Since that’s now the norm, saying “And it has a freezer light!” is an easy way for salespeople to try to sell you on a higher-priced unit. (Though in the age of smart refrigerators, that might not impress you much.)

[h/t Today I Found Out]

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