That is.... um.... a major cultural difference, it sounds like.
Between alcohol, tobacco, and weed, I think like 90% of coaches I've met consume a significant amount of at least one of those three.
I think alcohol consumption is very common here. It’s deeply culturally embedded as something we do, as soon as we turn 18. In my kid’s club it has a tangible presence. It is given as gifts, sold or raffled as fundraisers, consumed by parents when the team has dinner together during travel competitions - we even have a brewery located on the same property as the gym. I don’t know any coaches who don’t at least drink socially.
Weed and tobacco, on the other hand, are seen as a bit….I don’t know a word that would translate to American. The Australian word is bogan. But basically they are quite dismissively treated as not something somebody interested in sporting achievement would be interested in. I don‘t know any actual smokers under the age of about 45 (The stats say they exist, but they aren’t in sporting circles.)
WRT internet use, Gymnastics Australia has both enforceable policies and guidelines to help clubs develop and implement their own rules. The policy says coaches can’t ‘friend’ parents and children on social media, although there is a carve out for pre-existing relationships (you disclose the relationship to the club, so that everything is upfront).
The guidelines say that coaches and officials should carefully consider their personal social media use to avoid anything that may bring themselves, or gymnastics Australia, reputational harm (that is my paraphrasing of a page full of words). The expectation is very clear that that kids should never be exposed to something like Onlyfans by innocently googling their coach. (Which kids absolutely will do.)