That is because they are under the 4,000 distance band on the Aer Lingus Avios chart. (milestalk.com)
On the new system, Qantas have introduced a number of distance bands, and divided the ticket classes into a number types. (austravelpoints.com)
However, the roundtrip distance band goes all the way up to 14,000 miles, which means for no additional Avios you can add up to 3,024 additional flights miles on another oneworld carrier. (freequentflyerbook.com)