I look around me and see a vastly different group. Really it all depends on where you are. Get to the fresh vegetable section of the grocery store instead of the Doritos section and the people around magically drop pounds.
And yeah, public places had just as many “chairbusters” in the 70s. We just didn’t whine about it as much. Back in the 70s we didn’t think every hiccup in life was a crisis. There were fat people, there were skinny people, we moved on in our life. Maybe one of the biggest differences is unattractive (which includes fat) people were more likely to wind up on your TV and movie screens. So when you rant into them in real life they weren’t as jarring. Watch some Rockford Files or Kojak or Kolchack, you’ll see fat people all over your screen; in about the same percentage you saw them away from the screen then and now.
Go back a few decades further then. They existed, but not in current ratios.
I also think the problem is more about easily prepared pre-packaged foods loaded with both cheap carbs & corn fructose.