i think the cover is the LAST thing the client picks ... after the 8,000 proofs to 18 ...
THEN cover image is picked, the order goes to milan and it arrives soon after.
i shot a wedding** a few years ago and the cover image was embossed into the book-cover
it didn't go to milan,but to mN ...
i didn't get all the $$ up front ( should have ! )
and yes, i held the book hostage until i was paid ... and was like pulling teeth !
it was the last i might ever do ...
i do work for people all the time ( architects and engineers &c )
1/2 up front, half when the work is delivered, and sometimes they try to get the
images before i am paid, sometimes they add images, and i have to ammend the contract
... maybe i'll show them lo-rez proofs, i'll let them inspect the images, but that is about it ...
like the lady in the article --- its what they agreed to, no payment no images ... contract in hand ...
some people don't want to pay for what they agreed to purchase,
the way they agreed to purchase BEFORE the job ... the world is a strange one ...
** the mitzva went fine

the wedding was a pain.