I'm sure they must have many. I seriously doubt that all of any one person's emails go to the same person. In fact I'm quite certain that they don't.
But I thought amazon had a policy to respond within 24 hours.
Well.. I'm guessing Amazon.com's customer service "ratio" is somewhat similar to Microsoft, Citibank, etc...
Let's say you have 10,000 customer service reps. Potentially millions of customers. One item happens to be out of stock. 100,000 people ordered it.. Each of those customers sends an e-mail... And then there's another item that does not ship to another 100,000 customers... And so on and so on... You do math.
I'm not saying that justifies anything, but when you're one company dealing with millions of customers, there's bound to be a problem or two.. or thousand each day.