Most are just knocked out on a cheapo design package and sent off to the nearest lurid plastic printing firm, with very little design and no 'signwriting' skill involved.
I can understand that. But even in the slackest of operations there's someone with a vague bit of pride when it comes to the final result. Someone has to handle the file for output, consider a proof.
I've dealt with some cowboys in my time, but that's pretty darn unobservant.