It seems that using factors that cause good/bad job performance is normal hiring procedure whereas using factors that only correlate with good/bad job performance is statistical discrimination

So using things like test scores, impressions from interviews, etc., is statistical discrimination?

hmmm. Yes that statement is probably not correct. I guess your examples are observations that correlate with factors that cause good/bad job performance. Why is it more acceptable? Maybe because the link is much clearer/ correlation is much stronger?