For many people, the cost (both labor and monetary) of "good" coffee doesn't come with a corresponding increase in their enjoyment. You won't change their mind.
Instant coffee is not even in the same category as brewed coffee. I am by no means a coffee snob. I do grind beans right before I brew, but they are the lowest priced beans I can find that taste good to me (which is reasonably cheap).
I'd love to just microwave a cup, but that stuff tastes nasty.
I don't believe I have an impaired sense of taste. I'm just highly skeptical of the objectivity of my sense of taste. Marketting and branding probably has more influence than anything else when comparing two drinks in the same category (wine-to-wine, coffee-to-coffee, etc.)
Biased sample. There are many confounding factors why if you cannot tell the difference, it is likely your family can’t either.
I do like the idea of testing my wine drinking friends, who are definitely not snobs. I would bet money they would mostly pick the difference between a normal: Oaked Chardonnay, Reisling, Savignon Blanc, and Cabernet Savignon. I suspect the red wine drinkers could tell some of the red wine varietals too (I would struggle there).
Well, that's a bit of a strawman, isn't it, given it would typically boil down to "vanilla/not vanilla" for most chardonnays?
Coffee.. geeze, much more so. If the only thing available is a jug of brewed coffeewater that you pump out nice and bubbly, as at hotel breakfast bars or conference centres, I have to really 'need' it, and then I pack it with sugar to take the taste away. (I don't ordinarily drink coffee with sugar at all.) Instant, I just can't drink. I could definitely tell you the difference between instant 'coffee' and real, it's not a case of having a preference and better 'notes' like 'essence of snobby bullshit' - one I would be able to drink, and the other I would want to spit out before it even hit my lips.
I think you are concluding too much for the data points you have (of your personal experience).
I have a similar palate (lack thereof) like yours, but even my family members can tell when I've (say) used "too much" garlic in a recipe--when I can't even tell that the garlic is even there in the final product. (I only use it because the recipe says to.) Using a (e.g.) different marinade for chicken does not change my perception of it much when I chow down, but it does for others eating it.
I once heard the explanation that the 'flavour' of a food is made of the taste (tongue), aroma (smell), and even texture of a food. Adam Ragusa made a video on the smell part recently:
* https://www.youtube.com/watch?v=_O-E-7MMNyE
I suspect that I (and you given your descriptions) may have some kind of lowered sense of smell when comes to intaking foods and beverages, and so do not perceive the "tastes" as much as some other people. For example I cannot tell the difference in a lager, stout, etc, types of beer (they're all 'yeast water' to me), but I know people who love beer so much that if you put down a random one in from of them they could ID the style and often the maker and make.
The flavours that do not exist in your experience may in fact do so for folks who have senses that are more sensitive than yours. Epicurious has a series of videos where experts do a blind taste test on "Cheap vs Expensive" products:
* https://www.youtube.com/playlist?list=PLz3-p2q6vFYUpr-f2wOSQ...
There certainly are folks that pre-judge things by simply knowing which is which beforehand, but to say that 'there are no differences' is swinging the pendulum the other way too much as well IMHO.
Find a few coffee gear testing reviews where they use the same beans, using the same grinder, and yet different brewers cause slightly different results as perceive by the testers.
America's Test Kitchen is a good source, as they often have a dozen-plus folks do blind tests to find the most-liked ("best") product.
And I'm definitely not a coffee snob. But I can tell you that bog standard Tesco "house blend" coffee tastes nicer in a Philips Solimo machine than in an Aeropress, and nicer in the Aeropress than in a cafetière. And Amazon branded Solimo sachets aren't quite as nice as the ground coffee in the machine, but are good enough for every-day use.