I think part of the problem is that rich people in SoCal are different than rich people in other places, something you lay out clearly here. JP is basically a CA transplant, and carries his Ohio (Midwest) breeding with him. He's also ensconced up in Northern California, which is so much different than the southern part of the state. But if we take him as a model, he's got that old money breeding (like Wade) where status really doesn't matter to them. Why? Status, to them, is a birthright, and they have no need to earn it, or prove anything. My personal experience with SoCal rich people is that even after a couple of generations, they still act pretty nouveau riche. Robbie and Brad must be a bit of an enigma in Malibu, in that they've largely embraced the culture, but they have a different social background than most of their contemporaries.
I also think that the issue of public vs. private schools changed a lot over the 20 years we're talking about (1980 vs. 2000). If Isidore was at a Junior League brunch in 1980 and some woman was "bragging" about sending her daughter to a private school, she'd probably look at the woman with disdainful amusement, as if that would possibly make any difference in social status between Isidore's daughter and the lady's daughter. It just simply didn't matter. Besides, in 1980, motivation to go to private school was primarily driven by religion. In 2000, the issue isn't about status or religion, it's about getting the best possible education for your child. So I can see Claire at a similar Junior League brunch in 2000, asking the lady questions about her daughter's school and their academic creds, because that would be most important to her.
Jeremy,
For Tim, arguing is foreplay.