I’m ok with paying if it goes toward the NF. However, I recently purchased an Interagency pass, which, I believe, covers these fees. I could be wrong, however. $2 is really nothing, though. For those who don’t buy yearly passes, Acadia NP, which is local to me, is $25 a week. Which means if you hike every single day, it’s still almost $4 a day. Plus campgrounds are inexpensive but not free, etc. I don’t mind paying; as other commenters have said the NPS, etc. are underfunded and need the money.
But as I mentioned, one can also buy a yearly interagency pass, which should cover *all* fees into both national parks and national forest. And if you ask at your local national park, they may have a half-off day at the end of the year. Acadia does.