One or two sample citizen statements (such as callers to a radio station) is by no means representative of public opinion or public trends.
I find the above situation that very hard to believe. If indeed the teacher got in trouble as described (which may be an exaggeration), there must have been more to it.
I do agree with your point that parents and kids must communicate about the dangers of Internet use. The problem is that parents often don't know what their kids are doing on the computer, and, so many things happen on the Internet so fast it's hard for parents to keep up with the latest technology and abuse of technology. For example, a kid could be illegally downloading and distributing music and the parent might not have known that was even possible.
But I think overall there is a general blindness of parents and kids to the dangers of posting personal information on-line to any website. I strongly doubt any kid would post their beach pictures and personal info up on a public bulletin board in a mall or town square or share that information with a stranger. But parents and kids think the computer is somehow safer. This isn't only young kids, college kids have sites as well and share an awful lot publicly that they really should be more discrete about.
There is another issue of how much parental supervision is appropriate. When I was a teen, I would've been furious if my parents listened in on my telephone calls and would've been annoyed if they asked to see every computer printout I made. I think teens are entitled to some privacy. Unfortunately, the power of the Internet is so strong that comparing it to old fashioned POTS phone calls is apples and tomatoes. While my parents didn't listen into conversations, they knew at least who I was talking to and it was a peer friend, not some strange adult. Further, with most parents both working, there isn't much time to monitor all online, text-message, and cell phone transmissions.
Frankly, I think today's situation is unsatisfactory because people are exposing themselves (both figuratively and even literally) to danger via the Internet. But I don't know the solution without draconian controls and censorship that I don't like.
[public replies, please]