I guess that you're right, mostly. Initiatives to pass city laws against advertising do exist, though [1]. I don't live in Grenoble so i cannot comment on how this plays out in practice, but i wish all cities would do that.
The supreme court ruled that billboard bans based on location (for city and land planning purposes) would be appropriate, but billboard bans which determined which kinds of content were appropriate for public discourse were unconstitutional. A blanket ban across the state is constitutional, but a ban which targets certain kinds of content is not.
1. http://www.euronews.com/2014/11/26/grenoble-europe-s-first-a...