Earlier quoted context omitted.
You have to pay the VAT when you sell to EU even if you don't have presence in EU. Google pays that. The fuss is about some countries wanting more than that.
The customer pays the VAT. Google collects it and returns it to the government.
This represents a case of perfectly elastic demand. No matter how taxes change, the price the advertiser is going to bid never changes and thus all taxes will be off burdened onto google and facebooks margin until obviously the point where the would lose money and then shut it off but that's unlikely to happen.
khan academy article on elasticity and tax revenue: https://www.khanacademy.org/economics-finance-domain/microec...