Food safety issues related to eating raw frozen vegetables

I just pulled out a package of frozen spinach and noticed a warning "Cook from frozen, product must be cooked before consumption". I found the same on a package of frozen baby peas and I'm sure I've seen it many times before on vegetables that are often eaten raw when fresh. Are there any food safety issues related to this advice? I couldn't really think of a problem with vegetables that are commonly sold and stored a while at room temperature.