Washington D.C.'s anti-discrimination laws currently include political affiliation and source of income. Given that the city is home to a wide arrange of political actors from Congressmen/women to lobbyists for various causes, these laws were enacted so various industries may not refuse service to someone based on political affiliation or making money as a lobbyist for a cause they disagree with. Personally I wouldn't mind seeing this elsewhere in the nation, but I'm not sure if there are any other jurisdiction that does this in the U.S. There is talk about enacting protections against discriminatory protections against service for Uniformed First Responders (typically police) though most incidents I'm aware of this kind of discrimination are employees of fast food restaurants that will receive some public backlash that forces company higher ups to discipline the employee.
Certain chains of restaurants do offer discounts to members of a certain profession. Mission BBQ is very military and first responder friendly and will offer anyone who can show ID backing up their claims discounts on certain days (Military Service "Birthdays" and September 11. On Memorial Day, they set a table aside (complete with table cloth, candle, dishes, and a single red rose) for those lost in service to the country. Most famously, because their primary food product became so associated, Dunkin' Donuts initially offered free coffee and donuts to cops, giving police their trademark favorite food. This wasn't so much of a promotion as a mutual exchange of services: Cops (especially those working the Graveyard shift) typically enjoy their caffinated and sugary foods for keeping alert, as well as an occasion parking spot to write up reports... Dunkin' Donuts, one of the first chains to run 24/7 service in the U.S. needed some security (especially during the Graveyard shift, when robbers were more likely to cause trouble because of very few witnesses) and found that for the price of a donut and some coffee, they could have the city's finest sitting in their parking lot, sipping coffee and writing reports, for way cheaper than hiring a security service. (This practice was discontinued eventually as police forces saw these gifts as a possible corrupting influence and told officers to pay for their coffee. It wasn't that Dunkin' was bribing cops, so much as it was creating a bad image to the public.)