I think you need to look at the history behind those laws before you can make that claim. More to the point, the penalty for discrimination makes it less likely

I think you need to look at the history behind those laws before you can make that claim. More to the point, the penalty for discrimination makes it less likely that a company will keep someone who is prejudiced in a position where they hire people, as they're out big bucks if they get hit up with a law suit. You are correct that this may not do anything to change a racist culture, which is why many minorities leave certain companies after being hired, but if no one affected by a toxic culture ever gets hired, there's a very small chance that it will change on its own. And there's also the case you left out where the company itself isn't that toxic, but they left a racist in charge of the hiring and didn't realize it. This helps correct for that as well by discouraging having that kind of person in charge of hiring.