It's like this, a hundred or so people show up and set up camp like this and it's intimidating especially if the people involved are known to have unusual attitudes when it comes to the law and authority. If these guys are armed, your looking at manpower and firepower that is likely to greatly outperform your local police and most backup they could get, and even if they did show up in force if needed nobody wants to have a confrontation like that where they live.
Back in like the 1960s or 1970s large biker gangs/motorcycle clubs basically wound up ruling towns and even entire sections of the country for that reason since nobody could effectively stop them. According to some documentaries on TV, even now there is something of a 'truce' between law enforcement and some of the larger biker gangs who unofficially are left to self police. Largely because to deal with them would probably involve the national guard, martial law, and massive warfare accross state boundaries that would make what happened with Capone in Chicago look mild in comparison. I don't much care for the reality of this, but well, there you go. I was watching a documentary on TV talking about the two big groups down in California (Mongols and Outlaws I believe).
Despite how that sounds, I don't have any major issue with the Roma in paticular, and I don't say that because of any fear of curses or anything. I think the degree of problems/crime involved can vary from group to group. Ranging from harmless, to problematic.
I do however think that they should be using campgrounds and such, rather than just setting up near someone's house. I mean even if it's public property at least in the US your supposed to get permission from the local goverment before using it.
My overall opinions wind up being mixed, one one hand I feel the reception the Romany get in Europe is unfair and I was a bit miffed with how Madonna was received when she was performing with some Roma musicians. On the other hand I personally wouldn't want a hundred people from a rather extreme, migrant subculture, right outside my home either especially if they are (presumably) armed. Most people who claim they wouldn't be uncomfortable about this are fooling themselves I'd think.
Stories about curses, gypsies stealing babies, etc... are all BS as far as I'm concerned. On the other hand a subculture like that is by it's nature going to have to do some questionable things to maintain itself, and part of the whole reason for the migrant, nomadic existance is specifically to avoid law and regulation, and live by other principles (so to speak). Being people like any other, a closed culture like that, combined with the abillity to snub the law in most areas due to numbers and such, is of course going to lead to incidents as some people are going to try and take advantage of the situation. I mean even if you argue that the overwhelming majority are harmmless and respect the law for the most part, your still probably looking at a few in every band that are going to cause problems, and be somewhat sheltered as well. That's enough for the reactions in question.
It's not an easy issue to deal with to be honest, and there is no real moral high ground on either side of the equasion, it's one of those situations where it is what it is.
If I had to deal with something similar, I guess I'd ask the local authorities if they have the right to set up in that area, and if there is anything they can do about it. Bring some discrete attention to the situation and simply ask the police to keep an eye on things and do some fairly frequent drive bys, it's not all that unreasonable and part of their job.
While they weren't right next to me, I used to live down in Taftville where they let a Carnival (Coleman Brothers I believe) set up in a lot behind an old factory (Thermos). A little differant from what is being described, but the thing was that it had like a bajillion people going to the carnival going right through my aparetment's parking area, along with a lot of assorted rowdyness and people just hanging out on the street and so on. It was quite annoying. The police however had their eyes on it, and were pretty cool about responding when there were issues (though they didn't really involve the carnies themselves, which is what makes it substantially differant, but the point is that it was hundreds of people right there going up and down our street for days).