Backyard chickens are also statistically healthier than chickens that are commercialy raised in cages for their eggs. In fact, most battery caged, commercially raised chickens live about 2-4 years on average whereas typical backyard chickens live about 6 years.
The nutrient density in chicken eggs also diminishes over time as the egg ages and oxidizes.
According to fsis.usda.gov, eggs found in the store must be sold within 30 days of the egg being packed in the carton... which means, your eggs could be 1-2 months old by the time they are consumed. When you raise your own chickens, you get to eat eggs that are less than 24 hours old.
Chickens that have exposure to the outdoors also have a higher nutrient density in their eggs than indoor and confined chickens' eggs... Most chicken eggs that are sold in the store are from caged or indoor chickens.

However, most backyard raised chickens are cage free and free range (which means they have outdoor access and have room to spread their wings).

I personally notice a considerable difference in taste between my girls' eggs vs store bought eggs. Not surprising considering the facts here.