Why can yellow plastic wrap only be bought online?

Because the market demand is not high.

Yellow plastic wrap is not the mainstream option in the traditional physical store market, because most consumers prefer transparent plastic wrap and think that transparent plastic wrap can better observe the state of food. The market demand for yellow plastic wrap is low, and it is more difficult to sell traditional physical stores. On the online shopping platform, consumers can more easily find various styles and colors of plastic wrap, including the choice of yellow. This is because the online sales platform has a wider range of products and more flexible inventory management, which can meet more specific consumer needs.