To do otherwise would be to admit that we are either stupid or deaf. Still another reason is that most people haven't heard enough variations. Until you hear a system that can truly reconstruct the three-dimensional accuracy of a stereo image accurately, you may never realize that it is possible. However, we will never experience this until we are fortunate enough to hear such a fine recording on a very good system. Finally, some of us really can't hear much difference.
Some magazines publish lists of contact phone numbers for the manufacturers of equipment.
In the US, Consumer Reports has a small listing in each issue and a more comprehensive listing in their March issue. You can find many addresses by reading ads in hifi magazines. You can also find out by asking at your friendly local hifi shop, especially if you've built up a relationship with them. It comes out yearly and is available in some libraries. Many reps from parts distributors pass them out for free.