With respect, this is like saying “but the hard drive on Fry’s discount shelf only costs $100, why is your NVME-over-Fiber SSD storage system so expensive?”
Hint: what the consumer can buy over the counter, and what gets used in a professional setting, are frequently two radically different things that may only be tangentially related.
With respect, what you're saying is absolute nonsense in the context of ground rods. They're hunks of metal clad in copper and driven into the ground with a sledgehammer. They're so simple that there's literally no part of a modern PC that's analogous. The ones you can buy from Home Depot for $15 are identical to the ones I buy from a professional electrical contracting supplier for $15 - they come off the same factory lines from the same manufacturer.
There are other components used in contracting that have a bit more product segmentation, but the whole "frequently radically different things that may only be tangentially related" bit is wildly exaggerated. We use the appropriate components for the job, and often that means the same stuff you could buy at Home Depot. You're paying for that knowledge of what's appropriate/necessary and the labor to do the work, not for super-special premium contractor ground rods.
Hint: what the consumer can buy over the counter, and what gets used in a professional setting, are frequently two radically different things that may only be tangentially related.