The middle class has expensive weddings and vacations, but primarily is enslaved to owned cars/houses or educations that merely fail to be fully worth their opportunity cost.

I see quite a bit more stuff among the regular middle classes that looks like pure signaling waste, though you're clearly more knowledgeable how this compares with the analogous phenomena among orthodox Jews.

However, one very important issue you're not taking into account is that the primary objective that drives the North American middle classes to work their asses off is the need to afford living in an expensive enough neighborhood to insulate oneself and one's family from the underclass. (Clearly, various signaling and purely instrumental goals are entangled here.) With some luck and creativity, you can skimp on all kinds of signaling consumerism, but with this issue there's no joking, and it keeps imposing a horrible threat should you ever slack off. The lack of this pressure seems to me like a major point in favor of life in a deeply traditionalist community, so I think it counts in favor of the KJ setup.

Nonetheless, the body of ordinances, injunctions, and so forth that these people are expected to follow is amazingly comprehensive and capable of crowding out much having to do with happiness.

I find the orthodox Jewish observances a puzzling question: is it a matter of extreme runaway signaling that imposes excruciating burdens on these people, or are these just their natural folkways that merely look strange and arbitrary due to cultural distances? (Of course, it's a complex question whether and how these two things can even be distinguished in some objective sense. Many modern middle-class Americans would claim that they are more free than any other people in human history, and many of them undoubtedly really feel that way, even though from an outside perspective their lives can look frightfully regimented and devoid of any meaningful personal freedom.)