The 30mm sure seems to have a lot of dispersion for some reason. Too many rounds impacting well away from the apparent point of aim.
The P-51 and P-47 were also a lot closer to their targets - 100m to 200m vs. 1000m to 2000m for these attacks.
I think this is because they are engaging from far away. The Apache can use the 30mm from almost 6km.