alt Hacker NewsKatz serves roughly 3/4 lbs of meat. That is particularly big. You can get triple hamburgers which would be similar is size - but most people are ordering singles or doubles. And you can find other kinds of large sandwiches around the country ... but it is not the most common of sizes.
I think what made them not seem excessively large to me, is that it didn't really come with much else? Yes, it was more meat than I would get on a sandwich, typically. But... that is about it?
Maybe I got too used to some of the obscure burrito places around Atlanta that would put way too much on them?