In your latest comment, you say that "The whole point is to show that something non-local is happening". I'm not sure what thing's "whole point" you're referring to, but I suspect in the context of our conversation you're talking about the "whole point" of the implications of violations of Bell's inequality. But in that case, it's also not true that the point is that "something non-local is happening". There are QM interpretations that are entirely local, and compatible with the observed violations of Bell's inequality.
I found this paper to be a helpful breakdown of how the matter might be resolved, with some views embracing locality, and some rejecting it (some parts of the paper went over my head): https://arxiv.org/abs/1503.06413
People usually assume locality. I was talking about local hidden variable theory.
I was using unclear language to say something true, which is different from saying something false.
> There are QM interpretations that are entirely local, and compatible with the observed violations of Bell's inequality.
They are either breaking locality or doing something equivalent. This is getting into metaphysics, not physics, isn't it? Unless a conversation is deep into the weeds of quantum physics, I feel comfortable making answers that assume a particular commonplace interpretation.
We probably are into metaphysics. We're talking here about different theories that are all compatible with observations to date. Theory selection is very much a philosophical pursuit, though it's something physicists will do to.
Anyway, my main claim is that, as I understand it, the most popular or common QM interpretation (Copenhagen) embraces locality, so it's incorrect to say that "They are either breaking locality or doing something equivalent".
Here's an example of that from an article by Reinhard Werner ('What Maudlin replied to'), arguing (as I understand him) for locality. Some particles are entangled, separated, and then one particle is changed so as to impact (via entanglement) the other. However, the change on one to the other isn't real until later. "The state change only becomes effective when the results from the two labs are brought together and are jointly analyzed, which can happen centuries later."
In the other paper I linked you to, it has the realists (such as hidden variable theories) rejecting locality, with the operationalists (which, as I understand it, is the most common view) embracing it.
I'm being a little loose about casualty but that's because I don't want to write extra paragraphs about what "simultaneous" means.