Why is Google still serving dodgy ads?

Because the US refuses to regulate tech

But why won’t any other country do it either? Or are these ads only displaying to US IP addresses?

Because the US is aggressive towards countries that try. Also the companies are so large that they can exclude an entire country from their services.

A smaller country can take Facebook to court and might get a settlement but only a us court can truely punish them. With jail, breaking them up, law changes affecting their main customer base etc.