That, in a nutshell, is it. There is NO 'we're better than you' divide. That's all in your head.
The problem we've got in the NS is that you can't hear the fans on the left-hand side of the stand from the right. And vice versa. The sound travels easily towards the pitch, but not so well across...
This, entirely. It takes a while for the songs to ripple down from left to right across the stand, hence songs get started at different times. And I believe the police box actually dampens the sound, unfortunately. But there is no rivalry. The idea of such is just childish. The only 'rivalry'...