There's a couple of things in there that are just correlated to the fact that the author is around young/wealthy people, like the low obesity rate, fancy cars, shirtless dudes, book-reading in public. I had quite a surprise when I started working at a smaller town and consistently started seeing older and grumpier people.
Culture shock is real. For me personally, I didn't feel like I was going through anything unusual in my first 3-4 months in the US, but later a lot of my choices at the time made sense through that lens.