I will second the notion that indeed AA batteries, whether Alkaline, Lithium, or Zinc Carbon, for purchase by consumer at a super-market checkout, have not gone cheaper recently.
I will even venture that consumer lithium-ion batteries, such as for camera or laptop replacements, do not appear to have gone cheaper over last, say, decade. I can only assume healthy profit margin by brands (Nikon/Sony/Canon/etc, Lenovo/Sony/Dell/etc). Third party cheaper batteries are available, of dubious quality, so I suppose that may be a sign of cheaper manufacturing...
I'm not quite so sure about that. The prices have remained relatively stable, but the capacities have gone up. I think on a per Wh basis they may have actually gotten cheaper still. That means that you've gotten more battery life and/or more useful power in the devices that are using the batteries.
NiMH has the advantage of having very similar voltage to alkaline. Lithium ion AA batteries wouldn’t work as direct replacements in a product designed to be powered by alkaline batteries.
And it's an excellent example. Technology gets better until efficiencies are maxed out and battery cell production can't be an exception. The only big outlier has been computer chips, where slowly shrinking cost per square mm (if it even sank?) was an insignificant footnote compared to the ever increasing ability to pack in more per unit of surface area. Lithium batteries have far more in common with alkaline batteries than with transistors for logical operations.
Power transistors for example I would also consider closer to alkaline cells than to logic, there has surely been a lot of progress in that field which eventually brought us the miracles of HVDC, but on a far more conventional scale.
Most technology follows an S curve. It starts out slow with initial experimentation until most of the dead ends and pitfalls are eliminated, then there is a period of rapid growth as the tech matures and gains mass market acceptance, then it levels off with all of the easy gains mined out and you see only incremental improvements moving forward.
The middle part of the S curve is when you see the dumbest articles about the technology, with people extrapolating the growth linearly and talking about how it will rule the world in a few years.
