But the answer is obvious, isn't it? Information is almost free to reproduce. Food, clothes, etc. are not. I'm not saying that's why information should be free, but that's why most people expect it to be free.
But all the figures I've seen suggest that printing/distribution/remainders/etc. are in the low single digits so that even if you ignore any of the costs that are unique to ebooks, there is no reason for ebooks (or for that matter paperbacks) to be significantly cheaper than hardcovers other than price discrimination.
Even before ebooks, it used to be standard for hardcovers to sell at list price for a year or so at which point they came out as paperbacks selling for maybe half the price.
[0]: https://en.wikipedia.org/wiki/Paul_Samuelson
[1]: https://courses.cit.cornell.edu/econ335/out/lighthouse.pdf - page 359, first paragraph