Working a mobile car cleaner now, my manager asked me to take some
pictures before cleaning and after clearing, privacy issue of the car
California law creates an expectation of consent for taking photographs of people for purposes of commercial distribution of the image to the public. California Civil Code § 3344.
But, absent copyright or design patent issues (which would only very rarely come up since most people don't own the copyrights or patents to the designs of their cars, and the owner of the copyrights generally grants an implied license for the owners of the cars to display the copyrighted or patented designs), there is no parallel requirement of consent for taking photographs of things.
Furthermore there is no common law expectation of privacy in anything that someone you do business with must necessarily see with their own eyes.
So, if you must see the car to clean it, then taking photographs before and after the work is done does not violate any expectation of privacy to which the customer has not implicitly consented and does not violate any California or federal statute.
Better practice would be for the business to explicitly have the customers consent in writing to the photographs, to remove all doubt. But the implied consent to having someone see your car when they are cleaning it would be unreasonable to deny in almost all circumstances.
A company might voluntarily have an agreement to keep any photographs taken confidential and to have its employees sign non-disclosure agreements not to reveal what they see while working. If it did, this would create a legally enforceable expectation of privacy for the customer. For some VIP clients, this contractually enforceable discretion might be something that would induce them to pay a higher price for the same services. But those kind of protections are not the default standards of law that apply in the absence of an agreement. And, even then, taking photographs for purposes of internal use only would probably not violate an agreement of this kind. The work still requires that people inside the business, including remote supervisors, be able to see the cars to do their work.