How would the administrator be able to watch every single computer in the school at the same time? Someone would die if they pull this in my school. 40 PCs in the computer lab and 25+ netbooks per class.
Pretty much every student and staff gets given a computer by the school for me. That's like 800 people.
My school is really lax with it's monitoring stuff, partly because they put emphasis on trust, as you won't have people making sure you are doing the right thing all the time, and because the people who run IT aren't really behind on the times with internet things. The head of IT will actually let you get anything unblocked (within reason - nothing that would be illegal), even social networking, as long as you can come up with convincing reasons as to why and have a group of students who agree with you. Some people got instagram unblocked, and it isn't as if the IT staff don't know what that is. I think it was even students who got Facebook blocked in the first place, because they asked IT and said it was too distracting for them.
All your IT departments (and some parents) seem ridiculously strict.