(thank you lmao)
this is a tough one. i prefer global unions to national ones, but in a world where we do have such great differences in law and economy between countries maybe its currently necessary to keep unions national.
on the flip, that could lead to outsourcing to countries with lower costs of living, like you say... i spose a global union would set a price that is livable in the areas with the most comic industry activity / urban global north living - just because someone can afford to charge less doesnt mean they should, because it still devalues the work.
though the real issue is if someone is charging less and dragging everyone else down, theres not much we can do about it bc were global and atomised instead of being centred around one employer or place of work that can easily bar any outsiders to the union from getting employment.
i know that in film theres lots of legal requirements for studios and employers that are union-related, so i think in america you have to be part of the filmmaking union (??) to work on a set? similarly, you have to be part of the actors union equity to have a speaking part on stage or screen. so if a union gets big enough and holds enough lobbying power, things are possible. though i think thered have to be caveats made for like, children in their bedrooms and other novices working together