The holes in the fence are so that people can see in rather than climb over fencing. I was thinking more along the lines of work in progress/practices being uploaded onto the internet without them being aware. There is a difference in the Site Manager allowing an interested supporter a few photos and them being put up on a public forum, not to mention the subbies who I doubt have any idea of the photos. It would only take an unintentional photo of an unsecured ladder/unprotected excavation etc to get in front of the wrong eyes for problems to start.
Believe me, i'm not trying to be awkward here.