This is just applying the "mid-tech" folder insanity to fixed blades. How many production companies now are making top quality folders out of premium blade steels for HALF as much or less than we see "mid-tech" knives sold for, some of which are probably never worked on by the guy whose name is on them. Heck, we now have knife makers selling subscriptions so their fans can be first in the know and in line for their offerings.
It's marketing, and customers willing to pay the price. People buy that fixed blade strider, medford, spartan, etc. for $400+ because it's more unique, maybe they like the design or the company views/attitude, tacticool, etc. Just like mid-tech folders, as long as customers keep fighting to pay $500 for a production knife out of average blade steel, companies will certainly keep making them and pricing them at those levels.
I'd take it a step further.... lots of big production companies sell their fixed blade knives at similar prices as their folders. Perhaps that's because they won't sell nearly as many of them. I'm happy to be corrected if wrong but I doubt one larger slab of cheaper steel, 2 g10 slabs, and a sheath cost as much as a folder with premium steel blade, carbon fiber/titanium handles, titanium bits etc. not to even mention the huge amount of extra machining/assembly/adjustment/quality control time that goes into a folder.
I'll pick on ZT:
0620cf folder : 2 slabs of titanium, 1 slab of CF, M390 blade, titanium and steel bits, fasteners, washers, clip, etc. $240
0180 fixed: 1 slab of vanadis 4, 2 slabs of G10, fasteners, sheath $220
Just so I don't get jumped on by the ZT fan boys, I'll pick on BM too.
BM 810: M4 blade, 2 liners, 2 g10 handles, axis lock, various steel bits, washers, clip, etc. $180
BM 183: S30V blade, 2 g10 handles, fasteners, sheath. $180