This article on sdsu.edu explains the various factors involved in how far you can see towards the horizon. Besides the straight line distance, temperature and other artefacts of the atmosphere result in refraction that may allow an observer to see beyond the straight line distance at certain times.
According to the author's javascript calculator, two objects 74km apart where the tower is 305m ASL and the car park is 14m ASL puts the tower apparently below the horizon:
Finally, we find the apparent altitude of the target: −2.79 minutes
of arc = −0.047 degrees of arc.
However:
In your case, the dip of the sea horizon is 6.51 minutes of arc, or
0.109 degrees. These values place the target 3.72 minutes of arc, or 0.062 degrees, above the apparent sea horizon. The target is easily visible.
Reducing the target object altitude to 250m, the calculator still says that the object could be visible.
In your case, the dip of the sea horizon is 6.51 minutes of arc, or
0.109 degrees. These values place the target 1.18 minutes of arc, or 0.020 degrees, above the apparent sea horizon. The target is visible.
According to this smh.com.au article:
Our guides tell us at night you can see Norah Head lighthouse on the
Central Coast.
We're standing 260 metres above Sydney
Norah head lighthouse is 28m ASL, so seems likely that if that is true, so is the original photographer's observation (or theory).
Answer: yes