Here's my reason why:

While not on the same angle, or with the same size tyres, you can see the angle of my rear camber. Both sides were the same.
The fix?
Messing around with those three bolts until I was happy with the adjustment.
WayneO, when you change the bolt positions then put the rear end back on the ground drive your subi forward and back again to let the rear end settle - then assess the camber and go from there

Cheers
Bennie