You know what they say, 'As California goes, So goes America'. Enjoy.
1 Jan 2018 LA city council approved laws requiring street vendors get a permit ($$$). My guess is the city government told the police that they need the revenue and to begin actively enforcing permit requirements. I think these police may have asked to see the vendor's permit and then began the citation process when she couldn't produce it. Its also possible that a competing business in the neighbourhood called the city government to complain about a competitor that doesn't have to cover the same costs before making a profit.
That was a shake down plane and simple.