No.
In the UK (and Europe) we had BBFC ratings on some games, and PEGI on others. As a retailer, I am legally restricted from selling a 16+ rated PEGI game to someone younger than 16 or else risk a heavy fine, criminal record and prison sentance, as well as probably losing my job.
Now we just have PEGI ratings, and the great thing about those is that any game rated higher than 3+ (the equivalent of E in ESRB) has to have a reason why. Sure, a lot of games you might consider kiddy-centric and safe get 7+ and 12+ ratings for violence (Sonic Rush Adventure on DS gets a bad language use warning somehow, which intrigues me...)
ESRB does the same thing, but could use some more refinement and clarification, and if memory serves, they are mere guidlines not legally enforcible at store level (this may have changed recently, please correct me if I'm wrong) in the same way as BBFC and PEGI are in the UK. Simply making it against the law to supply a rated product to someone below the rated age would go a long way to redcing the problem, in much the same way that alcohol and firearms are restricted.
However, this doesn't solve the problem of kids playing games not designed for them. The day I enter a Call of Duty lobby and DON'T hear the high-pitched, possibly annoying voice of some 12 yr old kid (probably American) is the day when the proper responsibility is taken by all.
The great thing about having a solid rating system is that while some games can be banned (Manhunt 2, GTA 4 etc.) they are usually subject to a re-review and the programmers can change the game based on the feedback (one report on Manhunt 2 stated the reason for the ban was the amount of 'out-of-context extreme violence' i.e violence for violence sake and no other reason, it later got released with only minor tweaks). Because a game that is genuinely not suitable for a young audience is clearly labelled as not being, by a recognised governing body, it provides a layer of armour against the claims of sensationalist press. Little Johnny, aged 13, stabbed the school bully to death because he played too much GTA? Actually, I doubt it, it likely has more to do with Johnny's social environment and upbringing and the bully might have genuinely deserved it anyway for making his life hell, but the point to grasp on this is, if the kid really doesn't understand the line between fatasy and reality, then the parents or guardians have the legal responsibility to make sure he is shielded from influences such as graphically violent games and movies. As it stands, no retailer in the UK can legally sell such an item to Johnny anyway, so he must have got it somewhere else or by some other means. The industry itself is shielded from the argument because there are legal safeguards in place. Circumventing these safeguards is thus, effectively, a breach in the law, or just plain illegal.
While game ratings aren't infallible, they provide enough information to help people make the choice to buy them or not. Many parents come to my store and ask for advice and help on games that their child wants but are rated higher than the parent wishes to risk. I try to help as best I can, but at the end of the day, if their kid wants to play Call of Duty but hasn't even hit puberty yet, then I'm sorry, but even I am going to tell them it would be a bad idea, and not just because I don't want yet another 12 yr old on the server.
At the end of the day, there is nothing stopping games designers and console manufacturers from putting an age lock on their games. Its up to the parents to enable this system anyway, which is likely the fatal flaw in it. Anyone remember Leisure Suit Larry's method of preventing people too young from playing? Imagine booting up Halo 3 or Killzone 2 only to be asked who the President of France was. There'd probably be rioting in the streets.
