I do not know, but maybe the law, if it exists, is rooted in a compatibility requirement. AAA and AA batteries are single-cell and normally 1.2-1.5V, but you can never get that for lithium, even if you only use a single cell, since a single cell is always 3V or higher. That difference is large that it won't work interchangeably in any device. So for AA and AAA, that makes sense.Isn't it illegal to manufacture and sell a rechargeable Lithium battery that is the same size and same connections but different voltage as a Ni-MH battery? That is why there are no lithium rechargeable AAA and AA size batteries.
Tenergy batteries for RC airplanes are cheap Chinese ones sold only by HobbyKing. I did not know that the Chinese factory has an office in California.
Some of these 9V Lithium rechargeable batteries have a "protection" circuit board that limits charge and discharge voltage and current but others don't. But the specification says they all must be tested the same which is completely WRONG!
That is completely untrue AG, the 14500 is a rechargeable LiIon battery that is AA sized (I've just read the number off the battery in my LED torch). I've not seen any AAA sized ones, but on the other hand I've never looked.That is why there are no lithium rechargeable AAA and AA size batteries.