In just over an hour I can print a PDF, gather in a home made press, drill holes and sew it together with some bookbinding mull (open weave cloth). Then I glue a 2-3mm thick greyboard cover and attach a spine. Cover that with an A3+ printed cover to cover colour sheet and glue on inner (white though I have used coloured or printed pages) cover and a section to cover the binding and done.
A machine that could collate, drill, sew and make ready for cover attaching would be a nice little earner. Setup is the highest cost and ongoing costs for ink and paper with drill bits (snapped a few). Whether you could then charge enough to make a profit vs waiting for a couple of weeks for a Drivethru POD is debatable. Last POD I bought was Dragon Warriors, came in about a week. Quality is excellent as you'd expect.
Some books I've done vs POD. Edges might seem a bit fluffy on the books because I used Paintshop pro to remove/trim the background.
Covers are the sticking point and take a while mostly to decide on layout and where to position titles. I tend to customise those and quite often break bullet stoppers into separate books (all taking extra time/materials). Against the Darkmaster was split into 5 books and Deluxe Tunnels and Trolls four.
Where I won't print are books that are ink heavy like Mork Borg and those that have full printed background cover to cover. I much prefer books that are black ink on white background as my eyes aren't great these days, so there are a few limitations onto what I can print/bind. I suppose I could try but it would need pretty thick paper or expensive coated stuff. I generally use 120GSM which is thick paper (82lb in yank measures) down to 90 gsm (60lb) which just about prevents show through.
At some point I will pre prepare the cover ready to go on and see if I can print/bind/finish in under an hour. Glue drying time is an issue so a shop would probably say 'ready in x hours' I would guess.