Slaves need to be reminded what a privilege it is to serve their earthly masters.
And curiously, the bible says exactly that, which is very convenient
The two carts stacked with all the same brochures is about merchandising techniques. Its the same principle supermarkets use for end of isle displays for example...
I think you are giving the folks at Watchtower too much credit. I doubt it's well thought out. Each cart team probably just rather stand together so they can chat.