IMO: all public school should use
OpenDNS | Providing A Safer And Faster Internet
All parents who are concerned about protecting their children from the noise on the internet should use it as well.
You can proceed by getting in touch with the schools your children / grandchildren goto and ask them that they are not doing enough to protect them while they are using their lab computers, if the users are children.
But if they are teachers / administrators, then the privacy versus the urge to do something about it issue must be decided by you keeping in mind the comments by all the other members here.