The term "free-range" is not well-defined, and there is no federal standard for what it means. As a result, some free-range eggs may come from hens that are kept in conditions that are not much better than those in cages.
For example, some free-range hens may be kept in large sheds with little or no access to the outdoors. Others may be kept in small pens that are crowded with birds. In either case, the hens may not have enough space to move around or express their natural behaviors.
Free-range eggs are often marketed as being more humane than eggs from caged hens. However, there is no guarantee that free-range eggs are more humane. In fact, some free-range hens may actually suffer more than caged hens.
For example, free-range hens may be more likely to be exposed to predators, disease, and weather extremes. They may also be more likely to be injured or killed by other hens.
Overall, the claim that free-range eggs are the norm in supermarkets is not accurate. In fact, free-range eggs are still a relatively small niche market. Furthermore, the term "free-range" is not well-defined, and there is no guarantee that free-range eggs are more humane than eggs from caged hens.