I have always wondered why, for the entire year that the main grid had open registration, the Lindens never paused to consider the consequences.
By keeping the teen grid restricted and blasting open the main grid's doors, it is obvious to even the simplest of simpletons that a teenager looking for a good time is not going to bother to steal his/her parent's credit card and access a grid that is heavily censored and much smaller than the wide open, sex filled and uncensored, and gigantic main grid.
This is one of many curious things that Linden Lab has done that always confounds me. They complain about children being on the main grid. They know the consequences are that the kid is going to be exposed to lots of bad nasty things. Yet they make it easier for this kid to access the main grid. For almost a year, all they needed to do was lie about their birth date. Even toddlers will tell you that if you give them a choice of working hard for brussel sprouts or watch TV and get candy, they'll let you know which they'd choose.
Age verification is finally here (if a bit narrow and shaky: it only works well for some Americans). This should have been implemented much sooner. Why do the Lindens never think all the way through their decisions? I'm not one advocating information paralysis but to overlook this is just plain stupid.