The 30-minute flights continue past Manly to Dee Why and Curl Curl — the extra stretch of coast that the 20-minute harbour circuit does not have time for. From the air it is one shoreline, not a set of beach car parks.
This is from the air on the 30-minute shared and private tours only. You are not landing on those beaches. The 20-minute flights turn into the harbour after Bondi and the heads.