Self-audits never work, which is why there are regulatory agencies everywhere to 'double check' a company's work when ensuring legal compliance.
The real issue with this bill is that "addiction" isn't the same for everyone. The Twitter "trends" paradigm itself could be considered addictive if you really stretched it, maybe a 15 year old looks at it every waking hour of their day and goes through it all looking for tweets to reply to? Since the law doesn't only apply in a class-action sense, any parent could bring this to court with their anecdote and the court's main argument would be on whether that specific feature is 'addictive', not "addictive to all children".
For reference:
> An operator of a social media platform shall be found to have violated their duty if the social media platform is found to have addicted a child user by either of the following means:
> (1) The use or sale of a child user’s personal data.
> (2) The development, design, implementation, or maintenance of a design, feature, or affordance.
Quite literally anything could be grounds for the $25k + 2x attorney's fees in damages.
https://leginfo.legislature.ca.gov/faces/billTextClient.xhtm...