Why not?

You know, I think I would fully agree with you @roxy54 if most of the cables we are talking about cost less than $50 and very few more than $100 AND if we spoke of them mainly in terms of the materials, designs and workmanship employed. In other words if they were treated like normal wires. However we are talking about products that can cost as much or more than everything else in a system. These products are also treated as proprietary black box systems that reveal as little as possible about how they are made and what they are made of and what distinguishes one product from another, except for very general and vague market speak. They publish no test results, little or nothing about their physical make-up and often no rationale why we should even expect them to work.

We all know how much time and effort we put into researching and comparing products in the rest of our system. Many of us like to get under the hood and,usually, quality shows there as well as in the music made. Reviewers do the same for us, often including objective testing along with subjective impressions. Why do we tolerate less from cable manufacturers? Why excuse this category of product for making us play blind man's bluff? For these reasons I do not consider cable shopping part of the fun and am calling on equipment manufacturers to help us poor consumers make sense of all this. I believe they have the knowledge to do so and that the market would reward them for behaving like a no-nonsense square shooter. I like companies like that and bet you do too.

@bruce19 

Well, now you're starting in on a whole different subject, and what you're saying here is not wholly true either. Many manufacturers go into considerable detail about the construction of their power cords, and their reasons for making them the way they do. Whether we choose to believe what they say, or whether those techniques and materials actually make a difference is for the end user to decide.

Again, this is a different subject than asking why component manufacturers don't include fancy power cords of their own manufacture.

@roxy54  I know. You are correct, some provide more than others but as was said in another thread it is the wild west. I don't even have language to intelligently discuss cables because there seems to be no agreed upon language to describe what matters and what not. I am agnostic about cables. I buy them but I can't say with certainty what any individual cable has added or detracted from my systems. I have thought I have heard improvements but then on another day I may feel otherwise. The reason is it takes a long time to switch a cable and the changes, if any are subtle. Can't speak for others but my aural memory is just not that strong. I can hear differences in components but cables generally elude me. I bet I am not the only one who could say this if we were honest. This is further aggravated by my own tendency for confirmation bias. When something costs a lot that knowledge affects me, sometimes in favor of the item and sometimes against it. Have not figured out how to do blind testing on myself.

I have learned a lot about hi-fi in the past 5 years since I retired and am pretty satisfied I have at least a fair notion of what is going on in most areas, bought a lot of stuff, built some amps, built some speakers, etc. but cables are like trying to study alchemy.

And I bet I am not alone.

What's this "consensus" I keep reading about? Maybe here, but there are many, many other people who know that power cables produce no difference in the sound of your audio system. 

Why? Also, in the OP’s way of thinking, why stop at power cords? How about the interconnects, speaker, usb, Ethernet, and any other type of cable that might be connected to this device? Now you see the problem. Any of these cables can have a small to large impact on the sq of the system, so let the buyer decide with their own ears what sounds best