Is there any way that fast food could NOT have been invented & popularised to the extent that it is today?
Fast food has existed as long as cities has, so the only way, I can see it happening is if we stay hunter-gatheres.
There is a huge difference between sidewalk vendors selling hotdogs/vending machines selling stale sandwiches/etc. on the one hand and McDonalds on the other.
When I grew up, sure there were burger joints and KFC etc. on the strip. But most of these were drive-ins that shut down for 6 months of the year. Moreover, they were places where teens went and congregated. I remember the first McDonalds coming to town, and it was thought that Saskatoon, a city of ~150,000 was only big enough for one of them.
McDonalds was the first fast food place that was family friendly, and really, truly, caused a revolution in eating habits.
Pizza places, fish and chips, chinese takeout all existed, but you either phoned in your order and went to pick it up 20 minutes later, or you went and sat for that 20 minutes (a bit less for fish and chips, and chinese, but the principles the same.)
So, yes, fast food existed. But "Fast Food" didn't. Most of you guys have never lived in a world without fast food, and don't understand the difference, I'm afraid.
Now. Would someone else have created a "Fast Food" industry? Maybe, maybe. But I am not sure it is nearly as inevitable as some think.
It could easily have happened in some totally different way (sandwich vending machines, e.g.).