Descrimination cases are different. To win a descrimination case, the defendant must be proven to have engaged in repeated, documented, wrongful terminations based upon a protected status... age, race, gender, sexual orientation, ethnicity, religious beliefs... over such a period of time as to prove deliberate, descriminatory intent. There would usually have to be dozens upon dozens of people claiming they were descriminated against.
This is not the same as a company firing an employee they no longer wanted. For a single individual to win a descrimination case, there would have to be documentation of harassment based on their personal status, and incredibly stupid, documented statements that the individual was being terminated solely because of their personal status. That almost never happens.
Am I making sense?
Hundreds of thousands of people are terminated every year. Only a handful end up in court, and of them only a fraction ever win.