As this poster and others have pointed out, an awful lot of recyclable handling is done by, ahem, "hand."

This begins when you (the first set of hands) put the container either in a storage container or directly into your recycling bin. Unless it's a sealed container (and I doubt there are many of those) and you've washed out the containers, you now have a container full of intriguing smells that will only get worse until the day for pick-up.

If this is located in a reasonably sealed house or garage, maybe all you have to worry about are insects--at least for part of the year. But don't underestimate mice or other rodents, or even your own household pets. If stored outside, you can add a bunch of other critters, like squirrels and raccoons.

Virtually every employee of a recycling service can tell you that when they pick up and empty your container into their truck (second set of hands), the smell and infestation of the unwashed containers is anything but a joy to be involved with. Next, there are several steps in recycling (more sets of hands) to aggregate similar types of containers, pack them up, load onto a truck, etc., for transport to the plant that will actually process the material, including the baths that may remove the contamination.

Once in the processing plant, there may be one or two manual inspections (more sets of hands) before the container material is put into the process that often includes cutting or grinding, washing and heat treating. Later, the material is packed up to be sent to a customer that will reuse the material.

So, lots of steps, lots of sets of hands, lots of people exposed to noxious smells and infestation. This is why recycling is so damned expensive and only occasionally is it an economical way to handle containers. Whether it's better than landfilling has to be a local decision; the conditions are rarely exactly the same.