Compare BA to AA
Flight LHR-ORD-LHR, out 30/8 back 06/09.
AA flight on AA site - fare £331, extras £88.80
BA flight on BA site - fare £170, extras £249.50
BA extras includes fuel surcharge of about £150. So add that to fare and take it off extras.
AA fare £331, BA fare £320.
AA extras £88.80, BA extras c£100.
Not a great difference!