> _not_ to show ads to "undesireable" people, like people with kids, or of a certain religion

What if I have a bar in Vegas almost exclusively frequented by young people in their twenties who go their to get drunk and meet singles. Why would I want to waste money showing an ad to people with kids who will not be interested and bring way less conversions than people with no kids in their twenties? What if I open a delicatessen shop that makes most of its business on porc meat and liquor, would I get a lot of conversions by paying to show such an ad to Muslims or would I be wasting money? What you want is advertisers to show their ads to people who are not interested and lose their money. That doesn't seem fair to me. People of different family situation (kids or no kids) or religions don't always share the same interests and that's ok.