stickers > just looks cheap due to different surfaces and colors

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.