What does it take to show discrimination, if this is not enough?  The best evidence to show discrimination is almost always what we call direct evidence.  The "n" word, for example,  is always good evidence to show racial prejudice.  Using the term "old man" is very good evidence to show age bias.  So, this case where an employer refers to an African-American as "boy" several times over a two year period is very good evidence.  Yet, inexplicably, the 11th Circuit Court of Appeals affirmed the grant of summary judgment.  See Alexander v. Opelika City Schools

Summary judgment is where a judge essentially finds that a plaintiff (employee) does not have adequate evidence to justify having a trial.  To say that "boy" is not enough evidence to justify a trial is very hard to believe.  Frankly, many appellate courts apply an unrealistic standard for evidence.