I'm only one person. I can't explain everything. Do you have any idea why this divergence occurred?
I can explain the sexual revolution itself. The revolution emerged as a response to the introduction of reliable contraception, including highly effective oral contraception. It was one of those innovations that can and did, cause disruption. Societies are still adjusting. The US, with a population many times larger than the Netherlands, may adjust more slowly.
The Netherlands' conditions and circumstances are, in many ways, different from the United States. It is a small nation with an ethnically homogeneous population. It is located among other European nations on the European continent.
The Netherlands' population is 17,595,387 (12,275,791 in 1965). That is less than many US states. The land area of the US is umpteen-godzillion times that of the Netherlands. In the Netherlands, the entire nation is equivalent to "state and local" in the US.
Many United States policies are distinct from those of Europe (universal health care and gun restrictions, to name two). Perhaps these distinctions represent the "us vs. them" phenomenon that I described in one of my other comments.
I can't explain everything, but I can speculate. Do you have any thoughts as to why the Netherlands' and the United States' attitudes diverged in their responses to the sexual revolution? Does Amy Schalet?
"I can see how on a very macro-level that environment impacts how a culture develops, but there are just too many concrete examples of that not being the case for it to be such a sweeping generalization."
You have persuaded me to replace the term "environment" with "conditions and circumstances."
