Actually, no, parents are used to things not working out of the box and requiring additional power sources. Cause, you know, they buy toys for kids all the time. And a batteries can easily be more expensive than a 3DS charger. You are actually paying for what is in the box, your expectation to have everything you want in it is totes entitlement, so is your attitude as a consumer. That's okay, a lot of consumers feel super entitled. Most people who have ever worked retail know this. But, as I mentioned earlier, plenty of electronics do not necessarily come with everything you need to use it. So you are right, it isn't an American thing (even this situation is totally an american thing), it is a gamer thing. Or Nintendo-fan thing? To some, at least.
Also the charger does not power the device, the batteries do. The charger recharges the batteries, which are at least partially charged out of the box. I also bolded whatever riddle you left in hopes that you or someone else can decipher it.