Unfortunently, the "invisible hand of the market" didn't exactly work when it came to discrimination, and it rarely has actually worked.  For instance, let's take a look at two situations, and usually the invisible hand of the market just keeps in place the status quo, because that is what the community is dealing with.

1. Maryland repealed it's law requiring the segregation of public accommodations in 1951.  That means from 1951 through 1964, it was legal to desegregate your business, and serve black people along with white people.  However, the invisible hand of the marketplace did none of this, and it wasn't until the Civil Rights Act of 1964 passed that this segregation actually came down.  The Invisible Hand had 13 years to work its magic, and failed miserably.  In fact, the invisible hand of the market, could be argued, kept segregation in place, since Whites had the majority of the money, if you actually desegregated, you risked losing your white customers.