You're right. Honestly, I no longer give a crap about fairness. You will never get fairness in a competition where everyone doesn't play each other the same amount of times. And even if you try, someone will complain about it. It will always be uneven. But what you can do is create a draw and stadium allocation plan that maximises audience interest.
And yes you're right, with reciprocal membership access - Dragons vs Roosters, Dragons vs Tigers, Dragons vs Rabbitohs - they're all 25k (or more) games at the SFS. Similar will happen when Rabbitohs and Tigers shift games there too. And at that point the NRL season crowd averages will remain in the 20k's regardless of team performances.