If you are concerned that this is a public safety hazard, you should report it to Code Enforcement or the police department. They will know whether this is allowed, and will make the owners stop if it is not.
The opinions expressed are of general legal principles, and are not specific to the laws of any state or other jurisdiction. I am licensed only in California.
Food sellers and other retailers must have permits for sidewalk seating and/or serving, and the space and number of seats and tables is strictly limited. Contact your local police department or the staff-person for constituent services in your City Council district and ask that the retailer's encroachment be compared with the authorization on file for that use by that address. If the retailer's use of sidewalk space is within the allowed authorization, ask your city council district office to consider whether the authorization needs to be scaled back.
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Agree with the others, but add that if they are serving liquor, there may be special rules that apply that may not be applicable to other eateries, even if they do allow sidewalk seating. So check that angle as well.
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