Refrigerators are opened far more frequently because they contain everyday foods and drinks. An interior light is therefore particularly useful for quickly finding what you need. Freezers are often packed more tightly with bags, boxes, shelves, and drawers, which can block a single light and make it less useful.

Older freezer designs also had additional challenges. Freezers require substantial insulation and operate at much colder temperatures, while frost and ice can interfere with fixtures and switches. Adding another bulb, wiring, switch, and housing also increases manufacturing cost—even if only slightly.

Traditional incandescent bulbs also produced heat, which is obviously undesirable inside a freezer. Modern LEDs largely eliminate that problem, which is why plenty of newer refrigerators do include freezer lighting. So having no freezer light is not a requirement—it’s largely a design choice carried over from older, cheaper appliances.

In short, your freezer isn’t dark because light somehow cannot work at freezing temperatures. Manufacturers historically decided that lighting the refrigerator offered more practical value for the added cost.