Yes this is my issue with the whole thing.
The calculator say you get Avios and TP on the LOWEST ECONOMY.
So what deviants are there from "lowest"?
1. Nothing can be lower, so any ECO fare is at least equal to or higher than the "lowest" fare
2. If it's higher, then it's at least greater than "lowest" and it also qualifies
The calculator is giving misleading information!!