Apples need to be refrigerated. I cannot imagine anyone leaving a caramel covered apple
out on a counter. On the other hand, I cannot imagine taking a caramel apple out of the fridge and eating it. Good way to break a tooth, or loose a crown.
Have seen many a caramel apple out--and I don't see anything that woudl spoil
Caramel is candy. Apple is apple.
For Christmas one year our kids gave us a Williams-Sonoma caramel apple that--I kid you not--was a honeycrisp (maybe a Fuji) the size of my head!! Well, it truly WAS at least 8" in diamenter. We kind of shook our heads for a few days--and then started eating it. It was really delicious--but it did take a few days.
The REAL key is that they put a LOT of the listeria ON the apples and then were surprised
that the stick "inoculated" the thing.
The next statement is "listeria is rare in apples".
This IS a valid observation however in places where the sanitation is totally suspect. On a mission trip to Ecuador our group bought fruit like melons at the markets and then soaked it in bleach to disinfect the skin before cutting into it, and "injecting" any bacteria on the surface onto the edible parts.