Lottery systems are already used in some places, but they're very frustrating for those that miss out. Charging makes things less accessible to poorer people. I think tiers of experience are part of the answer - scenic shuttle/route at the easy end up to paid backcountry permits at the challenging end. Parks already do this but I think they could do more.
One thing that can make overrun scenic routes a challenge is parking for photo stops and I suspect a solution to that lies in changing the way people think about photos and documenting their experience.
It's probably changed since, but many years ago I hiked a couple of days in Tiger Leaping Gorge in China. There was a lower route for tourist buses and an upper trail for hikers. Upper route required greater commitment - better fitness, multiple days, guesthouse stop, etc. As both routes were on the same side of a steep gorge, neither was really aware of the other.
One thing that can make overrun scenic routes a challenge is parking for photo stops and I suspect a solution to that lies in changing the way people think about photos and documenting their experience.
It's probably changed since, but many years ago I hiked a couple of days in Tiger Leaping Gorge in China. There was a lower route for tourist buses and an upper trail for hikers. Upper route required greater commitment - better fitness, multiple days, guesthouse stop, etc. As both routes were on the same side of a steep gorge, neither was really aware of the other.