This is common to a lot of drinks, foods, scents if you haven't been exposed to a variety over a period of time and all you drink is the same instant coffee each day then yeah, the flavour is "coffee" and all you really notice is the volume dial on how coffee it tastes. If you start intentionally drinking different types of coffee regularly and actually try to notice the flavours then yeah, anyone can start to identify the nuances. Its hard to identify those different components and qualities unless you try different things where they have them in different ratios.

I'm personally really into tea and similarly when people say "green tea tastes like grass" its the same thing. I try loads of different ones and am pretty good at noting the various notes, stone fruit, honeysuckle, muscatel, minerality, milk etc. Yet to most green tea tastes like grass, oolong is that weird weak tea you get in the chinese restaurant and black tea is best served with milk and sugar by the gallon in a Sports Direct mug.

And maybe I'm not entirely oonga boonga on coffee but I definitely don't drink it enough to be good at being able to notice what exactly it is thats changing between them to be able to point it out.