I know my DD and her friends. I've known them for years. They don't drink, don't smoke, wouldn't take drugs. They play chess and scrabble, drink herbal teas and have an actual spreadsheet of their favourite blends, they go out and take photographs and edit them, watch documentaries, go to poetry readings and art galleries, do physics revision and mock Futher maths papers, they come and sit in the other room with me and DH and talk about politics and comedy and something funny they heard on the radio, they are young feminists, politically-motivated and socially aware.
They are never in the house alone. We are in the room next door or they're camping in the garden, ditto when at other houses, they're never home alone. I know their families. I know them.
They are smart, respectful, kind, mature young people and I am not naive, nor is DH, a copper of 16 years.
Please note that I acknowledged that some groups should not be trusted. I know what they do. They're pretty open about it in school. Some of them worry about it and approach staff for guidance. I know teens. But I also know my DD and her friends.