The only difference i see is, back in farming days in Iowa etc, it was pretty common for people to marry very young... but it wasn’t the age gap. ie 30 yr to 15 or 16.
My aunt and uncle married when he was 16 she was 15. They are still married today.. 70 yrs.
There hasn’t been the age gap on a systematic basis in America because in America a HS dropout has historically been able to make his way in the world, and been able to raise a family. Particularly when there was a frontier, and land could be obtained readily to support a family. But even in the past century, the ability to hold a job was your ticket. Your wife didn’t need to be qualified for a job - because after all, women were strongly discriminated against in employment.Now all of a sudden a woman’s employability is a thing. It even matters. Before that came to be, whose business was it if a man married an immature woman? Women were expected to be immature.