The proposed legislation:

https://legiscan.com/CA/text/SB244/id/2832427

(ii) A product or component of an “alarm system” as defined in subdivision © of Section 7590.1 of the Business and Professions Code. Code, including a fire protection system, as defined in the California Fire Code.

For the same reason you need a licence in most places to install fire and security systems. If you make a mistake, people can die.