What should be done about those who create parallel societies?

This is something I've been pondering for quite some time, but how should we deal with groups that don't want to integrate into society?

There are some groups, like the Roma and Jewish communities, that are closed and resolve their issues (potential domestic abuse, disrespect towards women) privately, with their elders acting as judges, never going to public courts, not to mention the real estate speculation they engage in. Then there are the Mennonites and Amish, who occupy fertile land where they produce far less than they should, and who face similar problems.

And then there are the indigenous groups in America who are allowed to live with old customs (child marriage, endogamy, patriarchy) but all of this while living in poverty and ignorance.

I've been thinking about this lately, because in my country there's a lot of "lumpenproletariat," and it's like watching people shoot themselves in the foot without knowing why.

By the way, I'm not against diversity; after all, I'm Catholic. But that's one thing, and another is that bad and outdated practices continue to exist, especially when the liberal state treats them like exotic pets and not human beings who need dignity.