Sure, forums are good for venting.
Not sure I can make you feel better, but I do have some comments.
Nursing in the South sucks. Terrible ratios and they even try to get away with it in ICU! Amazing.
It could have been worse. Most hospitals in both North and South Carolina belong to the SCHA (South Carolina Hospital Association), and while I've not heard of a SCHA unified blackball list, I know of two legal ways to create such a list. One is via a vendor manager, and the other is via a credit reporting workaround - this is what the Dallas Fort Worth Hospital Association does and creates a very stressful working environment for Texas staff nurses. Some very long threads on this issue in the Texas forum.
But certainly union area hospitals in the Northeast and west coast are better to work for with a contracted staffing ratio. California takes it one step further with a state law mandating ratios per specialty and acuity. Too bad about Eureka. I liked working there. The ICU is in a new wing, four or five years old now.
So the deal, especially in the South, is that it can take just one person (even a secretary as I found out in Miami) to be annoyed by you and you are gone (at least in hospitals that don't respect contracts). Travelers are disposable commodities as you have found out, and do not have a staff "family" get-out-of-jail-free card. So travelers have to be uber professionals in many environments to finish assignments. This doesn't mean that you were not professional, but be careful about everything, from tone of voice to how you phrase facts. Someone could have been pissed off by something as simple as you were more clinically capable and experienced than they were, and felt like you were talking down to them or lecturing from a better knowledge base. A very fine line indeed.
I have been in other hospitals where they respect contracts so much, it takes a lot for them to break it, even when there is clear incompetence. I remember one OR traveler in a Massachusetts hospital who clearly had never been in a hospital OR before (she may have been in a doctor's procedure room or surgery) and it took them 4 weeks to terminate her. They did it for lying on her application, not her incompetence. Perhaps they were lawsuit averse.
Anyway, the situations you describe do not allow for contractual termination for cause. Therefore, something must be falsified and they will make something up. As it happened to you. So I've been traveling for over twenty years and as you might tell if you read other posts of mine here, I have a bit of an "edge". So I have been terminated a number of time. I once had a director of surgery terminate me (again a secretary was involved, plus a specimen label that needed adjustment) and I mentioned that he did not have contractual cause. Honestly, they didn't really need me as the open heart surgeries they were expecting never ramped up. Low census is not a contractual reason to terminate. But he told me to my face that he would make up a clinical reason if I didn't accept it. That was pretty stunning.
You hear about these situations fairly frequently on social media. It is upsetting to be fired for any reason, especially when you are doing your job competently and advocating for your patients. The resulting rants make travel seem pretty scary. Fortunately, they happen less than you might think. There is a travel industry metric that says the industry average is that 1 out of 10 assignments fails to complete for all reasons. That includes your cancelled Eureka assignment. No way to know how many of those 10% failed assignments were due to "incompetence", low census, or "fit". Safe to assume some fraction though.
In my case, indeed one out of ten assignments does have a problem in twenty years plus of travel. But again, I have an edge. So with some prudent steps, the average traveler should be able to beat the average by a significant margin. Indeed, I know twenty year travelers who have never been terminated (or don't admit to it). I know of another very competent traveler who probably has an issue with every third or fourth assignment because she is not willing to bend her very high standards in work environments with lower standards. I have a good friend, about 12 years of travel experience who is very competent, but a major skill of his is his ability to get along (more important in general than clinical ability) - and yet he was terminated once for one slip. An ED nurse, two of his patients were coding and the charge nurse wanted him to pick up a new admit and he barked at her. That was all it took.
Protecting yourself means being proactive. Not just minding your P's and Q's on an assignment with everyone you interact with, patients, family, nurses, managers, and support staff: but having a good recruiter that knows a facility well and can provide honest feedback on how readily they are willing to terminate. Asking the manager why they need you during your interview can be revealing. High census, had a run of "bad" travelers, or overworked staff, or high turnover can raise red flags (versus the optimal pregnancy leave, vacation support, or never used a traveler before).
Anyway, sorry it happened to you. Get out of the South to have more reliably good assignment.