To adults? Mmm, besides the disturbing "Cookie", What else is direct to adults?
because the music they make are not aimed at teenagers or children, if they did, they would sound more like disney channel music than regular pop songs
Humans in general start developing music taste at 14 and it peaks at 25. Kpop fans are the same, while there are teenage fans of course, most fans will probably be around 18 to 20s. This is why groups perform at university festivals and not at school events. Apparently, according to billboard, 50% of KCON attendees were around 18-24 (even 22% were 25 to 34), with only 15% being teenagers, which makes sense.
If the members are 14 to 17, there's 100% chance their fans are going to be older than them. If the fan meet really was restricted to only fans the members age or younger, then they'll be excluding probably 80% of their listeners. So by design, groups with minors in it will encounter adults fans. At least if all members were adults, we wouldn't have minors having to deal with this situation.
This of course doesn't excuse the behavior of grown ass adults doing shady things at fan meets, which they shouldn't whether the members are of age or not.