I printed a large document at a popular commercial office supply company and they did not trim the document to my surprise, so it didn't fit where I needed it.
Is there a way to tell whether a printer prints at full bleed or if they trim the paper for you? Which is the common practice?
What may feel implicit to you would most certainly be expected by them to be explicit.
You get what you pay for.
You say "Can I have 1,000 of these printed?"
They say, "Yes, they'll be ready Wednesday. That'll be $25 please."
You say, "Can I have 1,000 of these printed & guillotined down to the crop marks?"
They say, "Yes, They'll be ready Thursday. That'll be $50 please."
The press & the bindery are two different departments - each needs paying for a task.
Take it to extremes... you wrote a graphic novel.
The entire job would be...
Colour-separations.
Making up the plates.
Set up on the press.
An hour & 100 sheets waste to get the machines in register & colour-balanced.
The print run.
Repeat the last 3 for each book section.
Guillotine.
Section; fold & stitch, sew, or glue;
Apply the cover [which would have been a job all of its own, plus lamination or UV varnish].
Edge trim.
Box or palletise.
If you paid only for the printing, that's what you'd get - a pallet of printed sheets - instead of boxes of books.
If you assume laser printing rather than offset litho, you still have to pay the bindery.
I only would add to Tetsujin's answer that some machines at "a popular commercial office supply company" probably do not register to the paper exactly.
A real offset sheetfed machine has a lot of mechanisms to have an exactly aligned print on the paper, so you can cut 500 printed papers at the same time. A bleed of only 2-3 mm is enough if the "large document" is not folded.
An office supply company probably have one digital copier, that probably can not align one print compared to the next one, so leave some generous bleeding and margin on your document. You probably need more than 3mm of bleed.
