I should also mention that the rechargeable AA batteries don't have the same capacity as these batteries, when tend to be less than 2000mAh when fully charged.

NiMH and NiCd are 1.2V when fully charged. Alkaline are 1.5V.  These are NMC lithium which are 4.2V when fully charged, but use a DC to DC buck converter to output 1.5V and simulate an alkaline voltage curve when they discharge

So this article basically compares apples and oranges. One battery is 1.2v, the other 1.5v. Both used, in a normal household, to two very distinct uses. So the price matter shouldn't even be brought up, as  AA/AAA 1.5v rechargeable batteries have been introduced just 2 years ago (?).
For cheap 1.5v rechargeable, Hornbach has them.