Modern hens have the broodiness bred right out of them, if they dont, or should I say wont set on a clutch of eggs, cause most will never- do so, nothing more will ever happen, the egg is just an egg and will never be a chick.  The cells only split and continue to develop when theyre incubated. People who make a big deal about the rooster being in the yard, and eggs being "fertile" just never seem to get that part, itll never be more than what it is, an egg.  
The rooster hangs around the hens, does his roosterly duty as nature demands he do, guards, fusses, eats, clucks and crows around the yard with them, sometimes the flock is happier with a rooster, I was always told they lay better
 Im rather doubting that these days, but I still keep a roo around, Im just picky about his breed, looks, attitude and nature now, more so than years ago anyway.
There ARE fertile eggs that come from the grocery store, some are labeled as such, but not always.  It may not be common, but there are certain producers that keep roosters too so they can sell "fertile" eggs (which do sell for higher prices) but if they wind up with more fertile eggs than the market for them demands, they just mix em in with the others.  They need only label them as such if they wish to, and if they do, some percentage of them MUST be fertile.  There's nothing to say that all fertile eggs need be labeled that way if they're on the shelf.