They don't have to show anything. The employee has to prove that it's age discrimination.
>When someone has been at the company for 25 years like in the parent’s example, and they get fired abruptly without notice for liking the wrong football team, it’s likely the stated reason is untrue and inviting a challenge.
Without a pattern of discrimination this isn't a problem. If there is pattern of discrimination then it is. However, if that's the case it doesn't matter how much documentation they have.
>It certainly helps show that the company isn’t discriminating arbitrarily, and gave the employee notice and a chance to improve the situation.
You can't discriminate arbitrarily. Discrimination in this context means firing someone because they are part of a protected class.
>gave the employee notice and a chance to improve the situation.
Whether you gave someone the chance to correct the situation or not isn't relevant.
>BTW actual legal action isn’t necessary for firing to be getting harder. The fear of legal action is all you need, and that is in fact going up.
The number of charges filed with the EEOC has gone down over the last 20 years https://www.eeoc.gov/statistics/charge-statistics-charges-fi...
https://www.natlawreview.com/article/eeoc-roundup-part-i-10-...
"At the same time, FY2020 saw the lowest number of charges received from workers in more than two decades. The agency received 67,448 charges—continuing the steady downward trend since 2017 in the numbers of discrimination charges filed with the EEOC."