Rebar in San Francisco has made a global brand out of Park(ing) Day, wherein curbside space is appropriated for the day as public space for pedestrians. That action has convinced the city to allow a few cafes to rent out their curbside spaces for additional seating, and Rebar thoughtfully created this buffered zone for Caffe Greco in North Beach.
Using the curbside space for seating appears to be popular in French-speaking countries; I’ve seen it recently in Switzerland and Quebec. However, it appears to be difficult to do in Chicago, since said public space is no longer controlled by the public. (I would think a private vendor would be more inclined to take a “rent check,” but the lack of imagination all around has not been encouraging.)