"Why do some ndu/cdo look down on other units arh?"
It happens on all levels of society. In school the NCC will look
down on the NPCC, who looks down on the Red Cross, the Scouts etc.
In adult life the BMW driver looks down on the Toyota driver
etc.
In the army, the training has to make you believe you are better
than others, tougher, meaner. faster, deadlier etc. It's all part
of the myth of soldiering. In order to succeed against impossible
odds you have to first believe that you can. Best summed up in the
English Special Air Service motto "Who Dares Win". If you believe
you can - you can.
The uniform, the habit-forming training, the weapons, the marching
songs etc all must increase bravado and the esprit de corps.
Some units like Guards and CDO's have stronger enforcement of this
spirit than others. And the result of this indoctrination into your
esprit de corps is to feel and act like you are better than
everyone else.
Some people take the indoctrination very seriously, some less.
Those who take it very seriously like a religion are usually people
whom had weak characters before NS. They were like empty shells.
Suddenly the army gave them an identity. During my BMT my
unfortunate platoon had 2 instructors from the now defunct "SAF
Boys' School". One of them was 17 years old.
These guys were like "Hitler Youth", mostly hopeless cases and they
signed up at 16 or something. So by the time they had got their
Ranger tabs and old enough to become instructors, they were
animals. But when I met one of them years later, the army had
kicked them out, and they gone back to being the empty shells they
were.