Why are equipment racks so expensive?

Having spent many pandemic lockdown months meticulously putting together my headphone system, it became very apparent that I had to get my gear off of the dining room table. So instead of chasing less expensive solutions like those available at IKEA, I simply went to the hi-fi store where I bought a lot of my stuff, and looked at what they put their $100K worth of components on. Yes the initial sticker shock was quite the slap in the pants, but after reading extensively I decided that investing in a five shelf Solid Steel rack was going to be well worth it.

...with prices:
Single A/V Racks (audioadvisor.com)
expandable, upgradeable

While the Lack is a very good shelf for next to nothing, Finite Elemente and SRA racks (examples I own) are better sounding and better pieces of furniture. I am not sure of the cost question. One is designed to be ultra cheap and mass manufacturered. A smart guy named Ken Lyons promoted their use. FE and SRA are much better pieces of furniture, sound better and not mass produced.  

Also the Lack is a shelf, not a unit. Solidity and stability was not the point. They are very light and rigid to yield clean bass.  "Solid" actually means nothing to me by itself as far as performance is concerned. My flexy was solid and sounded horrible.  

Some materials are expensive. So are labor and manufacturing. Precision costs money.

Anybody who has compared isolation platforms and racks, and isn’t as deaf as a post, will tell you some perform better than others.

Because someone will pay it, whether it matters or not. Like cables.