Several reasons for that. The primary one being that the compartment tiers and aisle occupied way too much very expensive floorc area. Compare that to the funnel effect of MacD’s et al. Also, customers felt free to ponder and look over the portions, slowly moving from one verticle tier to another and scanning up and down, looking, say for the best appearing slice of blueberry pie.
Secondly, people sat at the tables too long. The one I mentioned had several folks who seemed to be using them as offices, always there at the same tables with only a cup of coffee.
In the photo in post #24 everyone has a cup of coffee. Imagine how long they would linger if smartFones, tablets and laptops were around back then. Not even brick sized cell phone back then which is a crime against humanity!!!
Ah, no “soup Nazi” to keep things, and turnovers, moving.