This is the kind of superficial, results-oriented opinion that I don't like.
California's Unruh Civil Rights Act prohibits discrimination based upon sex, race, religion -- all the usual stuff -- as well as any other arbitrary basis. Lamb's Players Theatre (a local San Diego theater company) puts on a show and discriminates on the basis of age by offering a "[Baby] Boomer Night" promotion that gives a 50% discount on admission to only those people born between 1946 and 1964. So a couple of people who weren't able to obtain this discount -- even though they asked for it -- sue, alleging unlawful discrimination on the basis of age.
In a brief, eight-page (double-spaced) opinion, Justice McDonald holds that this discrimination isn't illegal because lots of statutes discriminate on the basis of age (Medicare, Social Security, etc.) in favor of elderly citizens, and that what Lamb's Players Theatre did was no different. And cites the California Supreme Court's opinion in Koire, which held that stores can permissibly charge lower prices to senior citizens, as well as other cases from lower courts that held that stores could rationally favor children (lower children's prices, etc.) or discriminate against them (e.g., not renting to drivers under 25).
Okay. But where's the case that says that you can charge older people -- your favored class -- higher prices? Remember, the 50% discount is only for baby boomers. So if you're born before 1946 (i.e., if, at the time of the show, you were over 58 years old), you're required to pay more than, say, a 45 year old. Where's the precedent -- or justice -- in favor of that type of discrimination. Justice McDonald says that it's fair to favor baby boomers because they're the ones likely to have kids and so a business can try to bring 'em in. Which is exactly the type of stereotyping and express discrimination that, in my view, the Unruh Civil Rights Act was designed to prohibit. On this view, why can't Dennys (or whatever) equally say "Well, we give a 50% discount to young people, but charge old people double our listed menu prices, because we want to bring young people in more often, whereas old people come here anyway." You can make similar hypotheticals regarding gender and race and any other category. California wanted to do away with precisely that kind of discrimination. The fact that you can come up with an argument that you want to "favor" a certain class doesn't make the practice of discrimination legal.
This is a bad case making bad law.
P.S. - It's also a little bit insulting. Justice McDonald says that the discount for baby boomers merely "acts to honor a generation of citizens who  have contributed to the economy and participated in and contributed to meaningful civic, cultural, educational, business, and recreational activities." Oh, really? The baby boomers did that, but not the others, eh? I guess the 60 year old who raised five kids and now helps with the grandkids contributed less to the economy and society than the 40 year old with five kids, huh? That's why it's okay to distinguish between 40 and 60 year olds; to recognize that the former contributed and contributes a lot more than the latter? Ditto for the difference between a 40 year old with five kids and a 35 year old with 5 kids. The former contributed more than the latter merely because he's older, huh? Right. That make sense. That's what we like to hear from our judiciary. Thanks for the kind words.
P.P.S. - I'd also expect more from Justice McDonald. You'll notice that I've agreed (here and here) with each of the other opinions of his which I discussed. This one, however, is of an entirely different quality. Plus, even as a personal matter, I don't see how Justice McDonald can really believe the stuff that he's saying. After all, he was born in 1936, and is almost 70 years old at this point. Would he really agree that his colleagues on the Court of Appeal who were born between 10 and 38 years are in a special category worthy of tribute because they have contributed more to the economy and justice and the like than his generation has? I'd be surprised if anyone held that view, much less Justice McDonald.