So what's responsible for the 440A craze and is it cheaper than the 420 that used to be the staple in cheap knives? And why doesn't it take an edge like the cheap 420? Do any of you have cheap knives you use around the house? If so, how about some photos? I'll try to get a few photos of mine if anyone's interested.
So, a few thoughts about the original question.
440A is used because then the company can advertise "440 Steel". There are roughly a gazillion regular knife users for every knife knut. Most of those non-knife-knuts recognize the term "440 Steel", even if they are clueless as to what that actually means. Using "440" steel is essentially an advertising ploy. "420 steel" means Zip-a-Dee-Doo-Dah to them.
However, for decades 440A was the most common choice for stainless steel used by American knife companies. Camillus used it in the vast majority of their stainless knives. Schrade called it "Schrade +" and used it in their Uncle Henry knives and on their other lines up until the late '90's when they switched to 420HC. Schrade is said to have heat treated their 440A to 58HRC. And at that hardness it performs pretty decently.
IMO, 440A holds an edge better than 420HC does when both are hardened to the same hardness. Rough Rider and Case both harden their blades to ~55HRC. RR uses ~440A and Case uses 420HC. RR holds an edge longer in my experience.
So, if 440A actually holds an edge better, why do many companies now use 420HC instead of 440A? Because 420HC is cheaper to process into knife blades. You can fine blank 420HC and crank out the blades at a tremendous rate. 440A does not flow well enough in the annealed state to fine blank well. That makes 440A much more expensive to process. Processing cost is a MUCH higher percentage of the cost of a knife than is blade steel material cost.
It's really hard to find anyone who produces 440A at high hardness today. IMO, partly because 440A has gotten a bum rap because so many companies run it soft.
Does CPM steel, 440C, D2, etc hold an edge better than 440A, even 440A at 58HRC? Of course they do. But 440A, even when run at 55HRC, holds an edge well enough for most non-knife-nut people in their daily use. And for the non-knife-knut, that's all that matters.
As to why you can't put an edge on 440A compared to 420HC, how hard did that knife company run the 440A? How complete was their quench during heat treat? Are the two edge geometries the same? Cutting performance is more than alloy choice. Heat treat and edge geometry are more important.