its a reality show meaning they tell people how to act, what to do, what to say. They are not paying camera people and production crew to follow people 24/7. They don’t have that budget. They just tell the cast what to do film for like 4-6 hours then do reshoots if needed.
It not really an invasion of privacy as these people are just cheap terrible actors. It’s all for entertainment and there is unfortunately a large amount of foolish who believe it all despite the large amount of evidence that proves it’s all fake.