Audio Diversity - What is it?

I've noticed that there are always alot of threads put up about "this vs that", tubes vs transistors, analog vs digital, cone vs electrostat, high price vs high value, cables make no difference, etc, etc. It seems that there is a wide variety of opinions as to what actually sounds good or better than the rest. Sometimes this elicits very strong opinions.

My question is why is it, that there is so much difference of opinion on this subject? Doesn't everyone hear the same music? Is it something to do with some other factor like, whether they never really heard many other things, or this was all their dealer had so they think it's best, is it listening skills, or what? Or is it ego, pride of ownership, and protecting resale value of their equipment, that is coming into question here? If that is the case, then are people lying about it to support their self-esteem or bank account, by exaggerating the quality of their systems to others? Do people who can only afford low-fi state that there is no difference in gear, only to make themselves feel better that they have just as good gear as the guy who paid $50k? Or are we all just imagining differences? Or perhaps, some of us don't want to get "closer to the music", but would rather have certain "airbrushed" qualities to it that they like, but take it further away from truth? Personal preferences? I don't know.

It seems to me that if 2 people listen to the same system in the same room at the same time, there should be some consensus about whether it is better or worse than some other system they compare it to. But yet, we seem to not be able to agree on this. There is always this and that getting in the way. But I say it's either closer to the music or further away. It should be easily determined. When 2 people look at a red car, they both know it's red. Nobody has to measure the reflected wavelengths to know that. One may like red better than the other, but there is no doubt that the car is red. Can't do that with audio systems. When 2 people listen, one says better, another says worse. Why?

What I would like to know is, what you think is the reason for such large differences in opinion about what sounds right and what doesn't. I don't want to start an issue about one particular type of equipment vs another, but I want to focus on why we don't seem to hear things the same.

I think this is at the root of alot of our discussions here on this forum, and I'd like to hear some opinions on it, which will likely be just as diverse.