In the late 1990's Orion and others sold some ED Doublets based on FK-5. The TeleVue Pronto was called an ED scope and was based on FK-5 according to Roland Christen. Technically this was ED glass but it provided achromatic performance.
I bought a used Pronto in 2002 for $775.
I think people still buy used Prontos thinking they offer ED performance.
In 2003, Orion introduced the 80 mm F/7.5 refractor we know as the ED-80. Initially the particulars were unknown and many suspected it would be another FK-5 fake ED. The price certainly suggested it, $500. But then it was stated it was based on FPL-53 and the affordable apo/ED revolution began.
Optically, the Type of ED glass used is important in the color correction. Manufacturers like Kunming United and Long Perng often make two versions of the same scope, one based on FPL-51 class glass and one based on FPL-53 class glass. The cost difference can be quite large.
Scopes like these are commodities, and sellers buy them from the manufacturers and sell them under their label. If I'm choosing between two 102 mm F/7 ED doublets, there are two options, those based on ED glasses with Abbe numbers about 84 and those with Abbe numbers around 95. The AT-102ED is an example of the former and costs $600, the AT-102EDL is an example of the latter and costs $1100.
You can read Roland's Abbe normal chart with annotations and see the longitudinal color errors of various combinations, you can look at Vlads polychromic Strehl pages, the differences in the color correction can be about a factor of two.
For someone shopping for a mid-level ED/apo, knowing what they're getting is an important part of the decision. Certainly there are other factors but the glass does make a big difference. Without that information, how do you choose between vendor A selling a 102mm F/7 ED for $1100 and vendor B selling a 102 mm F/7 ED for $1100?
Who is selling you the AT-102ED and who is selling you the AT-102EDL?
How do you evaluate a scope under the stars if you have not yet purchased it? How did people know the 2003 ED-80 was very likely to be far better than the 1990's 80 mm F/6.25 fake ED?
Some scopes have a well proven record. The NP-101 is not a commodity, it's a complex dual ED design known to have excellent color correction. But when you're dealing with affordable ED refractors, the materials used are good to know.
I've owned a number of affordable ED scopes, some with FPL-51 class ED, some with FPL-53.. there's a clear difference..
How many entry and mid level refractors have you owned???
Mine go from Vixen & S-W ST80 achromats as entry scopes to the S-W Equinox FPL53 Schott Ohara range for mid level (80 Equinox not as good as the ED80).
Disregarding price, my TV-85s & TV-102 are mid-level optically, but like 100 & 120 Equinox, they are good mid. Really for the magnifications I use, those 4 would be enough. I found out recommendations were good from use, then that the glass was mainly why.
I bought a TV-85 on the strength of my original Genesis and having a TV mount already. I was sceptical about Chinese scopes, until the Equinoxes proved themselves good, but also consider myself lucky. This scepticism remains deep so...
..I bought a couple of Takahashi apo refractors. Always a fan of Japanese lenses dating back to the early 1980s camera systems from Canon, Minolta, Tamron and Vivitar. My eyepieces are 60% Japanese, all makes, binoculars 80%. No disappointments. I trust Japanese made optics & QC/QM, they have earned it.
Similar with then East German v West German optics (had both) in the Soviet era.
Country of manufacture then/now has & continues influencing what and how much I buy from whom from 40 years as an optics consumer.