I noticed that the ground wire connects to everything. I wonder if the ground is actually necessary for the fixture? I mean, most street lights on wood poles are not grounded so this could pose a problem if the fixture needs to be grounded. I know yours is grounded though.

I'm not sure, the labels say the driver and housing must be grounded.

I guess LED drivers are more strict about the ground. I noticed that some electronic HID ballasts are also like that, they even had their own ground wire.

I guess the circuit boards are probably more sensitive to leaking current than magnetics.