Yep, health of the flock, age of the eggs, how they are packaged, time in transit and how the postal service treats them. I get my eggs on the third day from the day they are shipped, no matter where they come from.
Many years ago when I was shipping eggs, sometimes, it would take 3 days to get somewhere IN STATE but only 2 days to get to California. There's no rhyme or reason to it so it's not the distance shipped but what happens to it. And of course, they must be fresh, fertile and have decent shell quality or all is for nothing.