The main argument that I've heard from the (so-called, and YMMV but I'm going to call them that, anyway) Travellers about their breaching of clear Green Belt laws is that the site involved (the aforementioned scrapyard) is obviously not 'green'.
The main trouble with that being that the scrapyard ceased operating prior to settlement (though there's dispute about what this "green" land was used for, and by whom, in-between that and the settlement proper.
The Travellers own the entirety of the site, but mere ownership of the land does not convey the right to use that land for any purpose, even
outside of Green Belt zones. There are rules to be followed and much as there are people who try to get around them[1], to allow the Travellers to have broken them sets a bad precedent and encourages a lot of others to try to creep in under the radar. (This is the case in the UK, at least, but from another recent post on this forum on an unrelated issue, I know there are some areas where permissions are more relaxed. Even so, there's few places I would expect a chemical factory to put down roots without
some involvement of local, national or international authorities in granting permissions. If there aare any such freeform ones, they're going to be in one of the Bond Villain's traditional backyards, whether that be tundra, inside of the a mountain or undersea, I suspect.)
I have sympathy with all those looking to settle down, but it looks like mistakes were made by some of those residents being involved (which affected the rest) and I can't see backing off to be a good solution.
There's a housing situation in the UK at the moment (some blame Thatcher's selling of council assets to their tenants without using the funds to build replacement homes for those still needing 'social housing', something the latest resurgent version of this initiative is specifically going to be designed to avoid) but I believe honest efforts were made to offer housing for the illegal residents, elsewhere... The problem being (with reasonable or unreasonable grounds for objection, according to your POV) that they
were elsewhere, and not in the community. But compare with the 'nativel' residents of the nearby towns and villages where the children either have to continue to live with their parents (or their in-laws, upon marriage) or move out of the area.
It would be nice if everyone could be given their Carte Blanche to settle where they want (within nominal land-ownership possibilities, of course) but while there may well be a thought-crime level of discrimination against the Travellers, to give them a right that others do not get is equally discriminatory. The balance point may not be at the point where the current line in the sand has been drawn, but it's a line that those involved should have been aware of.
It is a point of note that the "legal half" was applied for, and obtained as, residential buildings and the council (although not necessarily the local residents) have had no problems with that. What is at dispute is the area for which the cpermission was refused and (as already said) building (and/or parking, of semi-permanent housing) on that area might have been better dealt with a lot earlier, but I suspect that a mix of unofficial sympathies, not wishing to appear heavy-handed and (at least in part) the settlement activities going unnoticed by those who
really should have known (being essentially camouflaged by the existing housing and activity) is the root of the problem. Maybe if Google Earth-type images had been as easily available, back then, this would not have come to pass. So it's obviously Google's fault.
[1] There was a case of someone who built an unauthorised house on his countryside plot, but hid it behind a haystack for enough time that when he finally dismantled that and objections were raised, it was beyond the notional time limit for objections and he (I think, I've not heard if it went otherwise since then) had to be allowed to keep it there. I think, from half-remembered details, that a lot of the legal confusion recently applied to Dale Farm's structures might be regarding which permanent structures pre-date the cut-off, and what is permanent structure and what is temporary[2] and thus subject to differing rules.
[2] There was another supposed story about a picnicing couple being charged for erecting a temporary structure without appropriate permissions... i.e. a windbreak. I only half-remember the details, it was a silly-season type story, anyway, so probably humorously represented in some way to make a Jobsworth employee of the authority even more ridiculous-looking.