You are correct...... having done signings with some players of different sports...... some enjoy doing them, some are indifferent and to them its simply business, some hate doing them and have no interest in signing.
There is an AFL player who despite being offered insane amounts of cash, simply does not want to or need to sign and turns everything down. One NRL legend is already being lined up for 2022/23 as a signer (very expensive signer) for when some more big time awards are being handed out.
With the resurgence of cards of late, more players are interested in it and most are willing to sign but some just don't want to or need to.
Signing cards can also cause issues between player managers - see Josh Hodgson autos in Powerplay many years ago!