On display sets for multiple hundred Euros however it just looks cheap due to different surfaces and colors - especially as no one is ever going to disassemble these sets.
It just feels to me like AFOLs poopoo on any set for having stickers, without considering the advantages stickers have from the POV from the POV of a child with few LEGOs and fewer dollars.
My #21334 is technically Ideas, not Icons, but it's in that same aesthetic sphere and it uses printed bricks.
My #10266 is the most "display-ish" set that has stickers, but it's also well within the gray area between "plaything" and "display piece."
#10298 Vespa 125
They are cheap!
To print on a piece you must run the inkjet assembly line, do QC on it.. With early Collectable Minifig series, I heard they outsourced that. I imagine inkjet lines that run all day for one piece type (maybe having changeable jigs.)
It's cheap to print a whole sheet of stickers!
Another approach that isn't so cheap is: in-mold transfer printing sheets. I learned about this at plastics shows around 2000; Apple used it on the all-in-one spotted iMac in 2001-ish.
Now since Lego ships perpetually ships 1x4s and 1x2s with black smileys or such, I guess carbon black in-mold transfer must be cost-effective. (That's a guess)
I know we're gonna be arguing taste in stickers forever.
I also have a set from another manufacturer that prints everything and there you don't have this problem.