Bicyclists aren't required to wear helmets in CA. As long as these scooters don't go more than 25 MPH I don't see why they shouldn't be treated any differently from a legal perspective.
https://www.dmv.ca.gov/portal/dmv/detail/vr/scooters
Here's the full text:
https://leginfo.legislature.ca.gov/faces/codes_displayText.x....
https://en.wikipedia.org/wiki/Bicycle_law_in_California#Bicy...
https://www.tracy.k12.ca.us/sites/bes/Documents/Bicyle%20Hel...
http://losangelesbicycleattorney.com/bicycle-helmet-laws-wha...
I wonder what they are getting ticketed for