In the 16th-century France, a poet Jean Daurat started an organised body of professional applauders called the claque. These people would be hired by theatre owners to seed laughter, merriment, crying, or whatever desired expression of emotion was appropriate into the crowd.
The rest of the paying audience knew full well what was occurring. But they simply didn’t mind. It was the way things were.
This seeding of reaction manifested again much later as the TV laugh track, (By the way, if you want to watch something truly odd, hop on YouTube and search for shows with the laugh track removed).
Our modern-day claqueurs come in the form of social media “influencers”. People know they are being paid to hawk skin cream and detox tea. Their applause is for sale, but people buy anyway.
Just goes to show how easily we can be manipulated by social proof, even when it’s in the open.