When Itzhak Stern points out the plight of the Jews relative to Poles to Schindler, he is performing two functions. Firstly, he is campaigning for the welfare of the Jews by appealing to Schindler's greed. The salaries of the Jewish workers was less than that of the poles and it was paid directly to the Reich workers. Hiring the cheap Jewish labor would reduce costs helping Schindler maximize profit. Secondly, there was an unspoken leading question that was meant to gauge Schindler's empathy for the Jewish nation.
