I'm with you on the privacy thing, but this topic has the potential of getting very serious. You're right about age-verification depending on honesty. COPA seems to require that 'adult' subject-matter be put behind age verification (which they are legislating as credit card access or digital certificate).
I've helped out with a site for a local Planned Parenthood and this could have serious ramifications on how they operate. All joking aside, how many of us have sites that might be 'harmful to minors'? http://www.eff.org/copa/
Back to the point of the OP: A webmaster can do whatever they want with their own site... their site, their rules. If he wants to use , it's his right to.
BTW: I clicked on a bunch of those google links and 9 out of 10 that weren't corporate annual reports, etc. redirected to an age verification page or asked me to relaunch the flash page that age verified me.