Is there an outside light on the other side controlled by the same switch? If so that would allow you to pick which one you prefer to have on when you throw the inside switch. If not, maybe there was a factory option to add other outdoor lights to that circuit?
... Now comes the question....Why would the manufacturer install a light up on the side of the camper that has a switch so high up, one needs and 8 foot step ladder to throw it? ...
Silly you, asking why a manufacture would do something. My experience is that there is no rhyme or reason as to why any manufacture does anything, other than to make more money. In the case of your light, my guess is they use the same light in all of their outside applications, cheaper by the dozen. The installer probably forgot to flip the outside fixture switch. Additionally, the people that did the final inspection did not do to well either.
Looking closely at the picture I can see that whoever created the "Caution" decal can not spell. The word should be "ENSURE", not "INSURE".
I am lousy at spelling, and typically would use "insure" not "Ensure". I looked up "Ensure", and unless I am missing something, both words mean the same thing. I guess it depends on which teacher a person had.