An interesting counter-point is that we designed our own wedding
invites, and when we got them printed the printers (a very large chain
in England called Prontoprint or something) wanted source documents in
PDF. They accepted PostScript if required but preferred PDF, as the
documents are less complicated, less prone to being targeting at
particular printers, and generally easier to print.
The same happened when I got some artwork printed on A2 card at another
large chain (Kallkwik this time): they claimed to accept Postscript but
when pushed (by mailing them CUPS postscript) admitted they import the
Postscript into Adobe Illustrator, so really want AI files. Or PDF of
course. I ended up sending PDF as neither Inkscape or CUPS would write
PostScript close enough to the PostScript that AI read.