Exactly this. I have chickens and when I collect the eggs they are usually completely clean. Only if I start to slack on cleaning the coop or one of the chickens gets sick do the eggs get dirty.
I can imagine most eggs sold in the United States would be horrifying if not washed.
The size of the nestbox can be a factor as well. If the nestbox is too large for the breed of chicken you keep, it encourages them to hang out inside it, and they walk on the eggs and get them dirty.
If a nestbox is the right size, it will only be used for laying eggs (and occasional brooding).
I can imagine most eggs sold in the United States would be horrifying if not washed.