If you were the FT steward during the male drivers' firings then why didn't you bring up the discrepancies in discipline at their hearings? If the male drivers' accidents happened before her last incident and too much time has passed then, as a steward, use this situation to your advantage. If your claim is true about her egregious accident record, then management has set the bar extremely high for any driver with multiple accidents. Discrimination is a violation of the contract and like any other violation it can be grieved - file or quit whining.
If the Union had done their due diligence in defending Ms. Ibarra, they would have filed a discrimination grievance on her behalf to argue the wrongful termination. In essence the Union did her a favor. Had the Union disclosed disciplinary outcomes of previous accidents in her defense, she could've have won at panel and been back working in that miserable delivery center. In the end, that decision would have been final and binding. Instead, the Union gave her grounds to file a lawsuit.
The bottom line with this company is: male, female, black, white, gay, straight, etc., management will get rid of you if they don't like you. Anyone who has ever worked for this company knows that. If you fall out of favor, they will put a bullseye on your back and go to great lengths to make your life miserable. Do you think for a second that when a supe decides to target someone, he stops and says "I wonder if I'll be violating Article 36 of the contract or Title VII of the Civil Rights Act?". I've seen management cost the company big bucks (missing pick-ups, etc), in their blind rage to zero in a certain individuals.
At the end of the news article appears the attorney's website and an email address. I would suggest, that anyone who has a similar story to Ms Ibarra's and can help her case, to use that contact info.