In the case of pre-prepared meals such as soups and sauces, it is usually not immediately obvious if it contains meat stock or animal fat. In order to read a list of ingredients correctly quite a bit of practice is needed. In addition there are even ingredients where it is not clear whether they can be classified as vegetarian or not. Animal fat for example, can mean not only butter, but also fat from slaughtered animals (although as a rule this type of fat is labelled). In the case of additives, E472 for example, and many others, it is impossible to find out just by looking at the ingredients whether a product with additives has been manufactured using dead animals or not. In addition there are ingredients of animal origin which, for various reasons, do not have to be declared: for example rennet, which comes from the stomach of a calf, is added to the cheese making process, or gelatine, for the manufacture of vinegar and fruit juices. Even after making inquiries about the critical ingredients with the producer and being very knowledgeable about food production, there is always the problem that the ingredients of a product can be changed unannounced.
Just one look at the V label will therefore simplify shopping for vegetarian products dramatically.