Your point isn't without merit, but your framing of it certainly is. The comparison made in the initial post is apples to oranges, but your experience is nothing more than anecdote and implying digital is universally cheaper is absurd. Allow me to counter your anecdote with one of my own:

Only a few months after release, I picked up an Xbox copy of Cyberpunk 2077, brand new from a big box retail chain and with a complimentary steelbook case, for $5.