Why does Francoise get upset with Vladek when she stops to pick up a hitchhiker?

One of the most interesting aspects of the story is the fact that Vladek, who survived the horrors of the Holocaust, is himself a racist. When Francoise picks up an African-American hitchhiker on their way back from the grocery store, Vladek can hardly contain his anger that she has let a "shvartser" into the car and spends the whole ride home watching his groceries to make sure they aren't stolen. This episode serves as a reminder that the racism of the Holocaust survives in other forms to this day.Thus the idea of race is only an artifice, Spiegelman suggests, and underneath the masks we are all essentially the same.