Which forest service campgrounds?
The only place I had to purchase a pass in the last two years was Sleeping Bear Dunes and that was $10 for the week or $20 for the year.
My visits to NF campgrounds along the Au Sable showed a use fee sign, but where we were at Sawmill Point it was included in the camping fee, from what I was told.
We were also traveling to many spots along the Pictured Rocks and never needed a pass, nor did I see any signage saying Fee Area. I am confused by the entire setup and never certain if I'll need it or not.