But IMHO you’re missing part of the scheming manufacturer’s equation in your “A” and “B” + “X” and “Y” theorising, and it is this:
Nowadays the more price-friendly inkjet printers from a number of manufacturers (most of them, in fact) come only with low-capacity or “starter” ink catrdidges supplied.
So you merrily depart the shop with your £50 printer thinking you’ve got a bargain, because the full set of ink cartridges costs that much - only to find that they run out after not very many pages of printing and you need more ink cartridges PDQ!
So while I agree with your theory in principle, the reality is that the manufacturers make it really difficult to make accurate comparisons.
And who is going to go to the time and trouble of testing and comparing?