Why do you think the ad network wouldn’t handle it similar to how payment platforms already handle sales/VAT?

It’s actually pretty easy to know which country an IP belongs to. ARIN, RIPE, etc all keep public databases tracking what ASN blocks are allocated to each country.

No, it’s pretty much only you thinking that. The rest of us were thinking about the 6 tiny bones in the ears only used for hearing or dozens of weird little bones in the wrists and ankles.