[joubert]

Aren't the ads displayed in a particular country from companies that operated in that country? When the user clicks on the ad the (French-based) company is charged by Google (i.e. the company advertising has now transacted, and according to tax origination principles, most likely that would be interpreted as having occurred in France).

See my other comments in this thread about the Amazon advertisers cases in California and New York, for a similar situation.