Why are companies afraid of litigation? My understanding has been that, excluding discrimination on the basis of a few protected categories, sexual harassment r

Why are companies afraid of litigation? My understanding has been that, excluding discrimination on the basis of a few protected categories, sexual harassment retaliation, and whistle-blower protections, in the US private employers can fire non-union employees at any time without cause. (IANAL) Are large companies really afraid of PR in firing individuals? If a company with many thousands of employees fires one person, outside of the C-level officers is that a news story? Even if disgruntled former employee tries to say anything disparaging, doesn't that immediately make them less credible as a source?