One of the main reasons why wooden pallets are safe for the food industry is because wood does not absorb chemicals. This is important for any type of food that is to be stored, handled, packaged, or thrown away after use. If a product is to be stored at room temperature, then it would not be absorbed into the wood, but if it is stored at temperatures above 120 degrees Fahrenheit, then it would. This is especially true when pallets are stacked on the ground, as they often do. The higher the temperature, the more likely the wood will absorb chemicals. click reference
Wood also does not react chemically with the foods that are being stored on it. It is very hard to tell if a wood product will react this way, as it could just be a bad experience for people who purchase a wooden pallet coated with chemicals and later find out that the wood has a chemical reaction with the food that was stored on the pallet. If the wood in your pallets is treated with an anti-freeze, then it will be even harder to find out if it has a reaction with any of the foods that you are storing on it. You could find out that you have purchased a product that is not safe for you to eat, but you may not know what the problem is.
When a manufacturer purchases pallets coated with chemicals, then they are simply purchasing pallets coated with a chemical. There is no reason for the food manufacturer to believe that their customers will not be allergic to the wood treated pallets, and so they must purchase the wood treated ones. The companies that are manufacturing the food products will need to purchase wood treated ones from a supplier that they trust. They do not need to purchase the ones from a company that they have never heard of, or from a supplier that they do not know much about. This can make a big difference in safety when it comes to purchasing and using wood treated pallets in the food industry.