>In a working market[1], the cost of a good is very close to its cost.

I would add a footnote in that comment.

[1] - A working market without large barriers to entry, information asymmetry, regulatory capture, monopolistic or oligopolistic companies, or basically anything else that deviates from the dozen or so different assumptions made in the "perfect competition" examples used in econ 101 classes that rarely exist in the real world.

I'm fully aware that markets don't actually work satisfactorily in practice.