problem with paint is that someone decides a particular brand/formulation/color is a good match... then the company discontinues or changes the formulation and everyone is back at square one again. with companies being forced more and more to become tree huggers and eliminate VOC's because muh environment and air quality, paint formulations end up being changed all the time... and these often change the color of the paint.
as for black... it's not a matter of getting a color right, black is black...for the most part... a lot of it is having a paint that matches the texture of a material that is not paint. see, old solid color arcade cabinets have a very thin almost paper coating that is the coloring...and also the texture of the panel. so not only do you need to match the color, you have to try and match the texture of something that is not paint...with paint. because the texture of the finish is also going to dictate how it looks in the light.
that said, i have black semi-gloss paint that i use for various things, and something changed in the formulation recently and the last gallon can i bought ended up being ever so slightly gray...so it's a very very very VERY dark gray... it's okay if i paint a whole cabinet with it... but if i just need to do the front or a small part of something, or touching up a ding, it's kind of obvious it's not the same color, so I end up painting the whole thing just for uniformities' sake. it is probably just an issue with the tint numbers in their system not accounting for this new formulation and the previous formulation differences and i'm sure the paint i buy today would be just fine. But be aware this is something that does happen.