A Steak N Shake opened in an NJ Mall about 10 or so years ago. I made a mental note to stop in to try it out, but it abruptly closed after a few years in business so l have never experienced it. I haven't seen any others in the Northeast.Where I live in KC there is a Steak N Shake that is fantastic. Never a lukewarm burger or cold fries. This place is run like a well oiled machine. Freddy's is across the street and it is horrible and twice as expensive. With all of the Smashburger hype these days, didn't Steak N Shake invent/do that decades ago?
There's a Freddy's in central NJ, maybe 5 to 10 miles south of Newark airport. It has been on my to visit list, maybe I'll eventually get there, but it will be less likely after reading your posting.