That's a Medium?

I stopped at Wendy's today to grab a chicken sandwich and a diet coke while running errands. On this stop I had a "Super Size Me" moment. I ordered the chicken club and a medium diet coke. The dude fills this cauldron of wax paper and sets it before me.

I ask, "Is that a medium?"

He looks at me with a smile and says, "Yes."

It's huge. Really huge. So huge, I bring it home for comparison. Here it sits next to a pint glass holding, well, a pint (that's 16 fl. oz).

The medium Wendy's cup swallowed the pint and another - Yes that's two pints! 32 fl. oz.! - with room to spare. I don't get it. Why do they do this?

-b