Because they know a good thing when they see it....but this does not mean you have "egg-eaters". As suggested, you may be having soft-shelled eggs that become easily crushed when other hens climb into the nest to lay, which they will promptly clean right up if they see the break and leakage.
I've fed my gals dirty and busted eggs for years and they have never developed into egg-eaters....but they do eat eggs when I give them or they find a broken egg. Check your egg shells for thin walls, provide supplemental OS and remember that during this time of year the egg-laying can get a little funky and you might see odd shaped, soft shelled, no shells, extra calcium deposits on the shells, etc. in your eggs. Birds are molting and a lot of their nutrition is needed for regrowth of feathers.