i noticed this when i first got my car and i actually thought it was pretty cool cos it would actually wipe away rain, initially i thought it was using the rain sensor but it seems as others have pointed out if you use the front wipers, putting into reverse it 'knows' that you used the wiper so will activate the rear wiper.
now it being winter i don't really want it to wipe unless i really want it to, also i don't want it moving if the wiper blade is frozen stuck to the glass otherwise the mechanism might break (means i'll have to make sure before setting off wipers are not stuck but it means spending time outside the car walking around checking whilst i don't really want to be spending too much time outside the car cos a) it's f**king freezing b) waiting car jackers might pounce)
although not really to do with the rear wiper, another annoying thing i find is the front auto wiper just doesn't wipe when i want it to, a normal timed-based intermittent wipe would just wipe every whatever interval, but on auto, even with the most sensitive setting i'll wait for ages whilst the rain just builds up and it just doesn't wipe so i get up getting annoyed and i'll either put it on normal slow wipe or pull the stick down past the off position to do a single wipe. sometimes auto stuff just gets in the way.
