I think a big thing is that many people want to get into camp because you're sort of allowed to do your own thing. Most people who get into camp, especially for the long haul and work up to being a director, aren't really interested in money. There's the trade off of working in beautiful landscapes and having free access to "fun" activities vs. making a lot of cash.
But going back to my original point, I don't think many camp directors want the extra help. Most camp directors are very "I can handle this all on my own". And that makes sense because at camp you do have to tackle a lot of problems on your own.
Most directors would probably see hiring a sales person as a giant waste of money. It probably isn't, though.