Can someone please tell why software like Paint Shop Pro is sold without the box?

I was wondering, does this definatly mean that the software is fake, or can there be other explanations? Since alot of the sellers seem to be businesses, on amazon and ebay and various others?Can someone please tell why software like Paint Shop Pro is sold without the box?
Those are probably OEM (Original Equipment Manufacturer)software and are intended to be sold only with new computers that already have the software installed and then to stay with that particular computer. The purchasers realize they only need one of the discs kept and sell the rest. The legalities are iffy.Can someone please tell why software like Paint Shop Pro is sold without the box?
cheaper why you need a big box for such a small disk makes since
they're saving paper

hair tips