>to your first question, the same that happens when a democracy turns into a dictatorship. Only since they are borderless it might be easier to leave the sinking ship.

That doesn't address my first question at all. Example of what I mean: Ted is in a community that outlaws stealing, but one day he's broke and really needs money for something important so he robs a 7-11. We'll say the 7-11 is in the same group for simplicity.

>What is most important is that community A has promised security against rape and will need to compensate Mary.

What are your implications here? Promised security? Recompense is not security, not that there's any real recompense for rape... plus people outside the community are able to create costs for that community in that way.

>Since your example is a quite extreme one it is easy to answer. Either community B makes Tim accept the verdict under community A's law and make it clear that B people are only allowed to rape other B people. Or B would get massive problems with all other communities and would be excluded from intercommunity cooperation. The other communities will apply economic pressure and no longer value other deals with B people. To avoid compensation payments higher security measures would be installed targeting B people.

It's not that extreme. Rape is pretty popular, there would be plenty of guys willing to be in such a community. Along those lines psychopaths would like join one that allows murder, pedophiles would join one that allows child sex, and I'd expect corporations to join one that has no pollution standards and doesn't allow the right to sue.

Now what you're saying is that these "borderless communities" have to impose their rules/sanctions on other communities. Economic pressure always *sounds* nice doesn't it? Except you're now trying to manage personal interactions using the invisible hand, which already doesn't actually do much. 

In other words: No one's going to stop buying their favorite coffee at Ted's shop just because he raped Mary. Just like no one stopped buying iPhones when they found out workers were treated so badly they'd commit suicide.

>In essence B people will be separated from economy have to fear for their safety and eventually have to move to a little island where they can all rape each other in peace.

Sounds like what we have now, but with more steps and confusion.

That's kind of the reality though: "Might" makes right, and in the end of society doesn't have a consensus then strong individuals will make right. With your communities what we'd very quickly see is a hegemon form that starts dictating what's allowed by other communities. That hegemon would be the wealthiest people, so we'd eventually end up with an oligarchy.

>In addition it is hard to imagine that you will even find a lot of people joining such a community. People are crazy, but not that crazy.

"People?" There are a huge variety of people all with their own thoughts on what's right. Remember women and girls are kidnapped all the time and forced into sex slavery. The Catholic church hid the rape of children by its priests. In Africa men are told that raping a woman is a way to cure AIDS. There are tribes, I want to say in South-America, where marriage is entirely based on kidnapping a wife from another tribe.

People aren't homogenous outside of their tolerance for noisy neighbors, they all believe different things and would want different laws. Some of the laws some people would want might be very dangerous to others.


>The hard parts are the little differences like neighbours complaining about too loud music...

No, the hard parts are all the interactions between people in person. That's literally what laws are for.

You mentioned Brexit for instance. What Brexit is largely about is that various groups didn't want foreigners living in Britain, right? So what group gets to decide who is allowed to live in Britain? If this community wants to force all people out who don't pass their "purity" test how do they accomplish that?