I agree. There are other rational considerations; they know there is food close by. They watch me cook so they know.They're very confident! If I were a chicken, I'd lay my eggs in such a nestbox because it's so safe.

Consider though, whether or not the hen is thinking about this when she lays that first egg here. Then consider that the pullets from the tribe who haven't seen a hatching hen in the nest will also try to lay their eggs here. That's a lot of planning!
It is also possible that the roosters encouragement to lay here, rather than elsewhere has most influence. You're left then with trying to work out why the roosters think this is a good nest site. I mean they don't sit here. They don't have direct experience of sitting and hatching here. They do come by and check on the hens but once they're installed the roosters even if they visit don't pay much attention to the sitting hen.
It gets more complicated. The roosters and hens pick their nest sites together in the cases I've seen. With the pullets, who haven't laid an egg they will tour prospective sites, sometimes a week or more before the pullet lays an egg. One or the other, or both must know the egg cycle is due to start.