Fare class determines base avios earning, status determines bonus earning. Bronze status has a 25% avios bonus of flight distance.
I suspect what you're seeing is when booked in discount economy (O, Q, G) earning 0.25x avios, they are earning an additional 0.25x avios. So for a 2,000 mile flight, you earn 500 avios and they earn 500+500.
See also:
http://www.flyertalk.com/forum/briti...os-2016-a.html