Oh they absolutely knew the pervy implications, they didn't think they would ever be caught:

https://en.wikipedia.org/wiki/Robbins_v._Lower_Merion_School...

"The school district intentionally did not publicize the existence of the surveillance technology. It also actively sought to conceal it.[23][41]" https://en.wikipedia.org/wiki/Robbins_v._Lower_Merion_School...