All I know is that few, if any, of the often empty seats around where I sit ever come up on the ticket exchange.
In any event, it matters little as the seats have been sold in the first place. The non-season seats are rarely empty in a League match.
The problem is that many people buy a season ticket to secure a seat for the big matches knowing that they will miss a fair proportion (maybe a majority?) of the matches. That probably suggests that season ticket prices are too low.
I know that doesn’t fit into the narrative that ‘it is all down to high prices’. However facts rarely come into that consideration.