When I started high school, which was an all boys school on the Gold Coast, during PE if we were swimming speedos were compulsory. Each there was a swimming carnival and every one who got in the pool wore a speedo, no jammers or dork shorts.
By the time of my final year I remember that guys were starting to wear jammers or the ‘speedo only’ policy wasn’t being implemented and guys were wearing dork shorts. I can only imagine that since then it has gotten worse with more jammers and dork shorts.
However, I was reading today a comment that someone said they were talking to a Speedo rep and schools were buying more speedos than jammers this year. I’m assuming they are talking about US but that is great news.