Printing can be a bit of a dark art, one important issue is the viewing distance.
Think of an advertising hoarding with a poster that looks remarkably clear from a distance, but close up the pixels can be the size of a cigarette pack. The same applies in art where one is often adviced to view a work of art from a set optimal distance.
Printed images work in the same way, so a lower resolution 48 inch wide image will look as good from a distance as a 10 inch wide image will look close up. It's convenient if a lower resolution camera is used to produce a large print and thus cheat the eye