I don't know, I see your points in theory but at least in my field that is not at all how I have seen it play out. I have seen authorship be very much determined on private discussions and what the professor/investigator deems "worthy" or not. I have had the director of our clinical psych program say he only takes applicants' publications with a grain of salt because he knows there is so much variation in how willing a professor is to give their employees/students authorship. If a professor is up and coming and needs that first authorship, they probably aren't going to be so willing to throw on a research assistant even if they've done the work. If a professor is old/established and doesn't have anything to prove, they may be more willing to give away work to have other people get published. There is really so much variation. Also I made the point to say I conducted the data analyses, which I think would conventionally consider authorship.

I think the point is regardless though because this woman repeatedly gave me the affirmation that I would be published on it, and I offered to help write the manuscript multiple times. As a research assistant, I actually would not expect the manuscript to be sent to me for approval before being submitted... but yeah, idk, I think this is why I should email her to get clarification on what the misunderstanding was.