They take dumb risks, the same kind we took as teenagers.
They have to learn not only academic subjects, but how to navigate life: how to hold down a job, drive, pay bills, and everything else an adult needs to do to survive.
If they wernt doing it in your house, would you prefer her doing it in a bus shelter or something? I would give them a call and see how they can help.
But you want to know whether they will be supervised on playdates outside of the house.