What Does It Mean When An Egg Carton Is Labeled 'Vegetarian'?
The question of eggs and vegetarianism is a sticky one, especially when it comes to labeling. Vegetarianism, and diets in general, are a matter of personal choice, and everyone is guided by their own standards and ethics. But eggs occupy an amorphous space in the world of animals and protein. They are found in the dairy section of many grocery stores, even though Delish notes they are not considered dairy, and as a protein, Harvard's updated food pyramid has them in the same section as meat and poultry. According to Good Housekeeping, because eggs contain no animal flesh, they are considered vegetarian, but some stricter vegetarians, and certainly vegans, consider them an animal product and avoid them.
So if eggs are considered vegetarian, why do they need to be specially labeled? Food labeling is a world of confusing jargon, and egg labels may be some of the worst offenders. As the American Society for the Prevention of Cruelty to Animals (ASPCA) notes, from the perspective of food ethics, egg carton labels range from truly meaningful, comprehensive terms like Animal Welfare Approved to the nearly meaningless, like "natural." A "vegetarian" label on eggs falls somewhere between these two extremes, as it does convey some information about your eggs, though perhaps not what you'd expect.
A vegetarian label on eggs most likely refers to the chicken's diet
Before making any claims about what vegetarian eggs are, it is important to note that egg-producing companies aren't faced with the same regulatory standards when claiming its eggs are vegetarian as when it claims they are organic (via The Spruce Eats). Since all eggs are considered vegetarian by most governing authorities, what the company is claiming likely has to do with what it's feeding its hens, and doesn't speak to how they are raised.
Delighted Cooking states that vegetarian eggs come from chickens who were fed a vegetarian diet. A potential problem with vegetarian eggs is that chickens are naturally omnivorous, and a vegetarian diet isn't actually healthy for them (via Insider). Chickens that don't get enough protein can actually get sick and start attacking each other. Organic and free-range chickens labeled "vegetarian" may be fed vegetarian diets, but the hens are likely supplementing that by foraging on the insects they naturally eat, which would make them healthier, but not technically vegetarian. According to Australian Eggs, hens that produce vegetarian eggs are often given protein-rich soybean meal supplements, but this necessarily means that the hens' diet must be carefully controlled and they aren't given the opportunity to forage.
All this adds up to a pretty confusing mix, but it's safe to say that vegetarian doesn't mean much on an egg carton, and may even be a label to avoid if you care about chickens' welfare.