I've just fallen into this trap for a second time. I booked a Sydney-Canberra red e-deal in the Qantas sale, and it came out as an E class ticket.

Obviously it's a matter of choice for Qantas and BA as to whether they give avios and TPs for any particular ticket. But I also have a choice, so while I had been considering flying back to Sydney (cost: $99 + travel from central Canberra to the airport, and from Sydney airport to central Sydney) I'm now going to take the bus (cost: $36, and it goes city centre to city centre). So Qantas have lost out on a fare.