Does anyone sell plain caramel apples that are suitable for shipping that don't have nuts or other toppings?

I've never seen any. Yes it does seem like the plain caramel apples are very rare. What kills me is when a site calls something a caramel apple, then you find out it doesn't have an ounce of caramel on it since it's coated in chocolate instead. The only plain caramel apples online that I found, like you said, were for local pickup only. Sorry to say, you may have to make them yourself. But get a bunch of family and friends together and make a fun project out of it.