Legal Question in Business Law in California

There is nothing illegal about this practice. California law says that the any business "may refuse to sell or serve alcoholic beverages to any person who is unable to produce adequate written evidence that he or she is over the age of 21 years." So when you go into a business and says they card anybody that looks under thirty, that is perfectly legal.

I'd go even further and say that any business can require identification before making a sale of anything, with the exception of Constitutionally-protected sales of so-called necessary items, where there would probably by a civil rights policy allowing anyone to buy the items without question. I think it would be commercial suicide for any business to ask for ID before selling, say, television sets for cash, but I see no legal reason why the business would be forbidden to make that a condition of its willingness to sell.

Duh. YES. ABC and the law requires ID verification to avoid sale to anyone that might, maybe, possibly be under age.