I see so I can follow you around and continuously 24x7 video tape and document your actions as long as it’s in public this should be fine.
Not OP, but yes, I think it is not. At least, not legal in the same expansive way that you are implying. AFAIK private detective work is very much regulated, most likely because it is otherwise known as stalking.
it is illegal because it means the stalker will attack / rape / otherwise damage or harass the victim.
however watching or tracking someone in public is plenty legal, and actual PIs have ethical and legal obligation to weed out stalkers and dubious behavior
Private detectives have an obligation to ensure that the intentions of their clients are legal if they want to continue to be private detectives.