(A printer can't get much more accurate than a 1000th of an inch...)
...and thankfully no-one owns printer with sloppy feed rollers or uses paper that is hygroscopic and actually changes size by a few nano-smidgens' when wet with ink or heated by the laser printer fuser (and shrinks a little ..)
With accuracy like that, why waste ink/toner on bleed margins - woohoo!

Those days are happily long gone...

(sorry - couldn't resist..)