Normally what is eaten is the object of transitive verb "eat"; here "eat" is intransitive and what is eaten is put in subject position. In this regard I think "eat" is following a pattern seen in other verbs in English. For ex., "I load the gun" but also "This gun loads easily"; "I drive the truck" but also "This truck drives like a car".
You might be thinking of the "middle voice" (a WR thread) (in quotes as not all accept the term).I don't think it's that unusual. Off the top of my head I can think of two: 'it reads like a book' and 'it spreads like butter' and 'they charge like a rhino'. Okay, so that's three, but the last one's slightly different. I'm sure there's a term for this device, but I've long forgotten it.
I don't think it was the comparative nature of the sentence that caught the OP's attention. It was clearly the intransitive use of a normally transitive verb, with the normal object in subject position, that was of interest. So the OP didn't care about the verb (would've asked the same question about "This juice drinks like wine"), but wasn't asking about the comparison (would've asked the same question about "The soup eats well").
That's the point I was addressing in my post above: guns don't load and trucks don't drive, yet we use these verbs this way.what makes it odd, of course, is that soups don't eat.