I'm not going to touch the racial aspect, purely the demographic discussion. No point trying to sell to a demographic who have no interest in buying your product. You need to appeal to the correct demographic and attract as many of them as you can. If you take the case of the mini SUV's, why waste money promoting that type of car in a break during Love Island for example when no one in the 16-25 bracket would touch them with a barge pole. No amount of advertising is going to change their mind.Surely the point of advertising is to attract people who don't already buy your product or shop in your shop? So why would you show the demographic that already does? Wouldn't you show the demographic you want to attract?
Advertisers want to target their key groups, they don't really care about the others. One of the reasons social media, influencers etc, is/are massively important.