While much is dictated by Mother bOrg causing an enforced "unity", in the real world many things are left to local interpretation.
From what I've personally seen, local culture plays a role in what is acceptable dress and grooming, as several mentioned. I've also seen where "fornication", "lying", and "stealing" get interpreted differently in another culture. I'll go with some cases where there should be "unity" but others just don't understand it the same. For example, to take something that doesn't belong to you is "stealing", right? Yet, in parts of Africa it was an ongoing problem that bethlites would take food and supplies from inventory, sometimes even money, for themselves or their families but didn't think it was "stealing" because they weren't attacking someone to get it. Also, others didn't seem to understand that prostitution is fornication. They figure that if she was willing and he paid, it was just business.
Even within a congregation, the rules can change when the CO changes. This CO thinks obesity is a sin and some lose "privileges". The next CO thinks that it isn't a sin, but a personal matter. However, he thinks that any dubs that work in the courthouse should quit. The next CO thinks that brothers should only have their hair or moustaches a certain way. Etc. So, the "unity" is there, but it's also not there.
If you want unity, try Coca-Cola or Pepsi in different parts of the world. Prices and packaging vary, but these brands understand the importance of unity and cultural adaptation.