I’m a fanatic of the 1960’s and I can promise you that baseball caps were normal then, especially for young people (kids-late 20’s).
They aren’t wearing em in the pics you posted because those are all ad’s for clothing and the company doesn’t make baseball caps.I’m not talking about young people, though. I don’t like young people.
The young people in the 1960s were typically much more likable and morally forward than the older people.
They also were a lot less fascistic when it comes to art, music, and censorship than their elders.