Well, duh. The markets can't correct racist government, and racist government was by far the biggest problem during the civil rights era.
Because the buses were segregated by law, not by private corporate policy.
Public schools, which are government-run and don't have a profit motive at all.
The only case you mentioned in which the racism wasn't government.
Funny thing: you haven't shown anything I said to be a myth.
Fail? No, I'm not arguing that they would fail, only that they would do worse because of that decision. In fact, I rather explicitly said that markets don't prohibit racism, I said they punish it, but punishment doesn't need to be in the form of failure, it can be in the form of reduced profits. Your question indicates you haven't really paid attention to what I've been saying.