As I will turn 65 next month I guess I qualify as an "old-timer".
My first fast food experience was in 1962 at the McDonald's on Wilmington Road in New Castle, PA: an original "Golden Arches" walk-up design with no seating. Their sign had changeable numbers that racheted up every time another million sold. Their menu was simple and everything was "one size": hamburger $0.15, cheeseburger $0.19, fries $0.12, coke $0.10, shake $0.19. Due to its novelty, we really enjoyed eating there; really though, the food hasn't changed much in the half-century since but the novelty has really worn off. And, "just because" I have tried McD's in London, Paris, & Rio: it is indeed the same everywhere.
Back then McD's weren't even the biggest bargain in town; that was the Red Barn about a mile south that sold a 3 piece chicken dinner w/fries for $0.59!
(Of course all that was at a time when I was earning $0.85/hr. as an after-school stock-boy/soda jerk at our local small town drug store
A few years later I enjoyed eating at the original Arby's in Boardman, OH (just south of Youngstown). It was truly wonderful, but the original sandwich certainly has changed over the years.
In the 1980's I was an enthusiastic patron of the first Five Guys, next to Brenner's Bakry in Arlington, VA. I remain their enthusiastic patron "down here" in the Metroplex.