The Megacorps aren't a united front, unless in the face of an existential threat like the bug spirits. Any plan that involves not selling stuff to people fails, because one of them violates the pact and sells to the isolated country. (And meanwhile another of the Megas is selling through backdoor channels as well)
I never saw anything about a joint-corporate operations against bug spirits (Aztechnology actually even withheld information about bugs for several years). Such threat are more nuisance that can be dealt with with enough firepower. As far as canon goes, the actual existential threat that make the corporate court presents a united front are the disruption of Matrix infrastructure (Winternight), destructive market manipulations (Art Dankwalther) and, most important, the defense of the Corporate Court own relevance, as exemplified by the following cases:
Corporate Download, page 10
> Back in 2045, the Corporate Court finally got aroun to promoting Wuxing from mere multinational to extraterritorial status. At the time, Wuxing had several key port facilities in the Canton Confederation. Some elements of the Canteonese power structre still held a grudge against Wuxing from the old Hong Kong independence days, and refused to acknowledge the corp's new standing. Wuxing demanded that the Court enforce its decree, and within three months the Confederation was reeling from "accidental" port blockages, power outages and food shortages, not to mention increased attacks from freshl armed neighbors. The crisis sparked a power struggle, and te old guard was thrown out. The new regime proved much friendlier to Wuxing and granted it increased privileges along with extraterritoriality.
> HK Kid
Sixth World Almanac, page 146
Rocked by sanctions from the New European Economic Community and the Corporate Court, the French government was forced to make massive cuts to their welfare and public health programs. [...] Megacorporations began closing down their local branches in response to the economic sanctions. Pressing for the repeal of the Loureau Act and formation of several pro-corp lobbyists, the megas left the French economy in tatters. With the nation facing the worst economic conditions since the Crash of ‘29, President Kervelec partially acceded to the Corporate Court and repealed parts of the Loureau Act. Eurocorps have begun to reinvest in France again, and formed extra-territorial compounds throughout the country, many clustered around Lille.
The thing is, the AAA know their seat on the Corporate Court is an essential part of their power. The system relies on the existing and emerging corporations
willingly submitting to the corporate court judgments in exchange for the guarantee of extraterritoriality around the world. The biggest threat to the Corporate Court would actually be that a number of large corporations manage to negotiate their own extraterritoriality accords with countries without having to recognize the court authority, deprieving them of their relevance.
-- Actually, most of the NAN nations are very pro business. Just pro THEIR businesses, and they generally don't recognize the Business Recognition Accords. So they keep a leash on the megacorps to some extent.
I would find it doubtful that none of the sourcebooks that cover etheir the BRA or the NAN would mention it. Both
Corporate Download and
Corporate Guide says only "a few nations" haven't signed the BRA, and list Amazonia, Aztlan, Manchuria, Tir na nOg, Tir Tairngire and Yakut. I think if the author bothered to put Manchuria or Yakut on the list, countries that barely existed in SR canon, if at all, at that point, he would have tell if a North American literally next door also was intended to be on the list.
The Publo is the only NAN in
SoNA described to some stringent regulations for corporations, but those are not much harsher than the CAS or the Scandinavian countries, so my take is they are compatible with BRA.
