When you receive a package from Amazon and the box it arrives in is comically large, it’s usually for one of two reasons:
1. When putting together an order, workers look at a computer screen that mentions what’s in the order and what size box should be used. Many times it’s correct, but often it’s wildly wrong. If the box is too small, the worker is trained to change the box. If the box is too big, the worker is trained to pack the item anyway and then fill up the rest of the boxwith dunnage (the filler material) because it’s faster than building a new box. The workers have a rate they’re expected to maintain (translates to one box every 30 seconds), and fiddling “unnecessarily” with boxes can affect it.
2. The item you ordered is considered hazmat, and is not allowed in a smaller box. Due to a law outside the company’s control, any object that is hazmat needs an outside marker so people are aware of it (one of the common reasons, lithium batteries, aren’t allowed to travel by air). The label has a barcode to be scanned to ensure that it’s there, and it’s placed on the side of the box so it doesn’t get in the way of the barcode that’s responsible for prompting the shipping label. If the side of the box is too small, it’s not allowed for hazmat items, even if the item being shipped is super small. That’s also why you’ll never receive hazmat items in envelopes.

I worked on The Truman Show back in the 90s and it was ridiculous. You had to keep smiling all the time and pretending everything was perfect. It was so fake. I just wanted to yell "Knickers!"