Here are for and against on average based after round 23 (21 games for each side):
1. Eels 57.9% (158 for, 115 against) F = 7.52 A = 5.47 Diff = 2.05
2. Souths 55.7% (142 for, 113 against) F = 6.76 A = 5.38 Diff = 1.38
3. Sharks 55.4% (159 for, 128 against) F = 7.57 A = 6.09 Diff = 1.48
4. Raiders 53.5% (151 for, 131 against) F = 7.19 A = 6.24 Diff = 0.95
5. Broncos 52.3% (137 for, 125 against) F = 6.52 A = 5.95 Diff = 0.57
6. Cowboys 52.2% (155 for, 142 against) F = 7.4 A = 6.76 Diff = 0.64
7. Warriors 51.3% (137 for, 130 against) F = 6.52 A = 6.19 Diff = 0.33
8. Dragons 50.5% (138 for, 135 against) F = 6.57 A = 6.43 Diff = 0.14
9. Bulldogs 50.4% (134 for, 132 against) F = 6.38 A = 6.28 Diff = 0.1
10. Tigers 49.6% (129 for, 131 against) F = 6.14 A = 6.24 Diff = -0.1
11. Manly 48.7% (151 for, 159 against) F = 7.19 A = 7.57 Diff = -0.38
12. Titans 46.2% (133 for, 155 against) F = 6.33 A = 7.38 Diff = -1.05
13. Panthers 45.8% (121 for, 143 against) F = 5.76 A = 6.80 Diff = -1.04
14. Storm 45.5% (127 for, 152 against) F = 6.04 A = 7.24 Diff = -1.2
15. Roosters 44% (117 for, 149 against) F = 5.57 A = 7.10 Diff = -1.53
16. Knights 42% (113 for, 156 against) F = 5.38 A = 7.42 Diff = -2.04
So in otherwords, the actual difference between most favoured team and least favourite team is 4 penalties per game...
It's not a massive difference in the scheme of things.