Not that I intend to excuse the obvious waste, but there are at least three reasons that are probably considered by manufacturers and distributors. Large packaging on small items is both to provide a big enough space for their advertising, and also to deter shoplifters. Large shipping boxes for small items is probably to avoid shippers losing tiny packages in machinery that isn't designed to handle them.
Not that I intend to excuse the obvious waste, but there are at least three reasons that are probably considered by manufacturers and distributors. Large packaging on small items is both to provide a big enough space for their advertising, and also to deter shoplifters. Large shipping boxes for small items is probably to avoid shippers losing tiny packages in machinery that isn't designed to handle them.