The UK is (was?) also a mostly Protestant country. My family is a mix of Catholic and Protestant, and I’ve only seen this from the Catholic side (not actually in my own family, thank goodness). Certainly I don’t know any English Catholics from high school who dropped out to marry. I also don’t know a lot of fundamentalist Protestants, which I suspect would be a different picture.
The other thing you’re not taking into account is that this report is about the US, and I’m concurring from Canada. The people I knew were all children of parents who immigrated in the post-war wave.
When I was in high school we used to talk a lot about “stuck in the 50s” families, who thought they were carrying on important ethnic traditions in the new country while the old country had sensibly discarded them decades ago.
Or, as one of my friends put it after visiting her aunt and uncle in Italy when she was 18, “my 13 year old cousin is allowed to stay out later than me.”
Finally, as pointed out elsewhere in this thread, we’re taking about a small but not non-zero percentage. The vast majority of girls in my high school got married in the adult age range you mentioned. It’s not the norm to marry at 16. My point was it’s not unheard of either, and it’s not just people from the third world.
