Look at the incentives. Google makes money from scam ads. Most ads I see online are scams of some sort. If Google completely blocked scams, they might not be in business.

Yes I understand that Google says they care a lot about scams and that there are people there working on blocking scams. But those are words. We need to look at money.

There is a very simple way that Google can block basically all scam ads: review all ads manually before approval, and allow no dynamic changes. They won’t do this, because it would implode their business model.