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Salaries at summer camp, like many other areas, largely depend on age and experience. For example, a first year 16 year old in aquatics will be paid less than an 17 year old that has lifeguarding experience, even though both teach the same swimming merit badge.
In addition, some summer camps charge staff members for a "staff kit" of t-shirts, staff hat, etc. Some charge for room and board. Some give discouts at the trading post for staff items. Some camps, due to state regulations, pay by the hour. Some give discouts at their council scout shop for uniforms. So one camp says "We'll pay you $ 100 a week" and another says "We'll pay you $ 120 a week" Which is the better deal? You say $ 120, but then you find that the staff kit costs $ 50, and you don't get paid for staff week, and there's no food available on weekends. The $100 a week job gives you two nights off, 3 t-shirts and a hat, no extra fees, food for Saturday night and Sunday morning, and for takedown week, you only work 3 days and get paid for the full week.
One other reason is that at a summer camp, like a regular workplace, salaries are confidential. If a staffer found out that another staffer, working the same job, was being paid an extra $ 25 a week, it could cause moral problems.
Finally, most don't like to talk about salaries because they are so low.