The loops are isolated at the crossovers.
Just using Insulated Rail Joiners is not enough. It only takes a lapse of concentration and have one loop set to DC and the other set to DCC and then try and run a train across the cross-over and you will end up connecting the outputs of the DC and DCC controllers together. This has the potential to do permanent damage to controller electronics.
Are not all the brass wires shorted together in this image or is it an optical illusion due to the camera angle?
Optical illusion, they are separated vertically. Correct on the DC + DCC. I generally only plug the DCC in on its own and toggle the 2 loops to that controller.