At some point platforms should be held responsible for the ads they run and the damages they cause. If the ad is to be broadcasted to thousands of people, or worse targets groups of people, it's reasonable that it must be approved and vetted by the platform. The cost of such vetting, even if done manually by a human, is likely a fraction of what is the cost of creating an ad anyway. If necessary Google can charge advertisers with an upfront cost.

Edit: grammar