As someone who lives many hours away from the park but visits several times a year, I too zeroed in on the $40 annual tag as being pretty dang cheap.
A typical trip for me involves to nights in the back country. So that's 3 "days" I need a parking tag. 3 trips like that a year and annual tag pays for itself compared to the $5 daily fee.
But dang, now that I think this thru, GSMNP is going to be getting expensive.
If I take three 2-night trips to GSMNP in 2023, I'm most likely going to be taking my son along, and back country fees are PER PERSON
So that's $32/trip in back country fees, or $96 + $40 in parking fees: $136
I'm going to be pissed if I have to start paying that much to camp in the back country if I don't see some sort of positive change in a few years (better trail maintenance... beyond clearing downed trees and over grown brush, but more importantly, I want to see more rangers in the back country ENFORCING the rules).