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.
What did we package things in before disposable plastic became ubiquitous? I don't think I was alive then. Or did we just have a lot less small and single serving products?
Chocolate bars used to be folded aluminium foil and paper. Some still use those materials but now they weld (crimp with enough pressure?) the foil which is probably better for the product but OTOH it's slightly annoying because you have too little foil to re-wrap a bar you only took a little bit off of.
I think they're still wrapped in foil in Australia, though I haven't had any in a few years. I don't think I've ever seen any eggs come wrapped in plastic, although the bags the foil eggs are in are plastic
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.