What world do you live in where anti-discrimination laws aren't already aren't already utilized by the employers you've referenced? It's really hard to get fired as a US Federal Government or Union employee (based on what I've seen from both in a Midwest state, for United Auto Workers) and the EEOC has had historically strong support for employees for the entities I've cited.
Private entities will do what they've always done and my original comment succinctly describes the default outcome. Nothing has changed.
That's some pretzel logic there. They can't arbitrarily implement/enforce rules without first disclosing them, and it looks bad in a court of peers if they start doing this haphazardly. I would actually say it's easier for them to get away with this in an at-will environment without these rules.
"Position was eliminated" works pretty well (in the US).
Continuous recording and decent resolution = $15/month. Pricey, but it is what it is.