I think the term "printing" was coined by professional, gun-savvy LEOs (i.e. Massad Ayoob) who zealously enforced their local concealed carry laws by coming down on the sloppy carriers. Generally, I think their motivation was well-placed, as a bunch of complaints of brandishing would make concealed carry permits harder to justify politically. The extent to which this actually occurred, relative to the number of lawful permit holders, was never clear to me.
That was before the surge in the last couple of decades that saw many states open up this mode of carry. I am skeptical how important this is to the average LEO on patrol, particularly where open carry is legal.
And with so many people carrying cell phones and the like on their belts, I don't think it is on the average person's radar at all. Besides, they are too busy talking on the cell phone to notice anything anyway.