That is useful information for you to put in the bank. The light click you hear is the door control module switching in power & ground to operate that window. So, based on that, you know that the door control module is powered up & at least it is switching and that there is inter-communication (serial buses) between the driver door & rear doors. The fact that the front windows operate normally tells you that the 30A bkr for all power windows in the rear fuse block isn't tripped. With all that being said, it would appear that you have possible failed regulators which you probably have already figured out. Follow the links that Archon posted, they will be of great help.

Very faint chance that someone didn't want the back windows used and unplugged the motors...

Million to one I'd say..but I'd have that luck