I've looked up fermenters, and most are pretty expensive. I see that most people use food grade plastic buckets. Just out of curiosity, is there a reason these are better than something like this?

I have no idea, so that's why I'm asking. I'm sure there's a reason for the way things are done. I know the price of that particular jug above is much more expensive than a bucket, but is that the only factor?
I also know that it likely won't have as good of a seal than a plastic bucket, but I'm sure a rubber seal could easily be fabricated to seal the lid to the bottle. If you can put a hole for an airlock in the plastic bucket, to release gasses, seems like you could with this too.