I, for the record, don't agree with the "I know it when I see it" rule because of that and I find it impossible to prove direct harm caused by virtual depictions of child sex. (And apparently "virtual child pornography" is legal in the United States provided that it is not "obscene." No idea what that's supposed to mean...)
Well thats clarification for you. Clarify one area that is vague with yet another vague/subjective concept.
For a non-anime fan a lot could be considered obscene I would think. But if you have been watching the stuff since one night in 2005 you decided to stay up all night and decided to watch "family friendly" Cartoon Network in the early morning hours, your standards have been lowered (a sort of "I've seen worse mentality").
The other problem is, as was stated earlier, a lot of it is based around portraying children in adult positions/roles and/or foist a lot of "adult responsibility" on kids (...Usually involves saving the world), combine that with a lot of "fanservice" (sexual gestures and revealing clothing), as well as some nudity (which is actually visible if it is uncut version or if it is from the 1990's) and thus enforcing this gray area that nearly all animes delve into at least somewhat (with a few exceptions), may have been deemed impractical. A lot of this can be found in programs that are either unrated or TV-14 with a few exceptions, usually if there is extreme violence (which kicking someone in the head/and or ripping their heart out in the form of some kind of weird magical crystal or something I suppose, seemed to be acceptable Saturday Morning content in the mid 2000s in the US. That audience starts at 8, though that isn't as bad now I think).
Also, and getting back to your early comment about the inability to detect age, people on the internet have produced "images" shall we say of characters from these shows that also opens up a whole discussion about copyright violations as well. These characters are often altered in the images to look older then they were in the original material.
