Each bar is wrapped in cellophane, which are then wrapped in the normal outer packaging. To make the 4 pack, they simply took 2x two packs and put them on a cardboard tray,and then wrapped those.
I don’t think I’ve ever gone through so much unwrapping for candy.
Many things didn’t used to be packaged at all, they were sold loose in bulk. The shop would put them in a paper bag at purchase.
Come to think of it, nowadays you can still buy certain things in bulk, but a packaged option exists too. You could carefully choose and weigh the individual potatoes you like, or you could just pick up a bag that was prepared earlier in some potato factory. The same things applies to many fruits and vegetables too.