It's also up to the private business to enforce its own requirements. All the BPC provision does is state the minimum standard which will permit a business to avoid liability in California.

The unfortunate problem, as others point out, is that the people who do the grunt work are minimum (or close to it) workers. Sure Nexus is a USG-issued ID. But, if you want to make it simple, you tell your people State DL or Passport and that's it.