If you had to name just one thing that stands as the biggest difference between the 60's and 70's and our modern day, you might as well say "smoking". It's hard to imagine, unless you were there, how omnipresent cigarettes were back in the day. You were never more than a stones throw away from an ashtray.
Game show hosts took long hard drags while they did their shtick, people smoked on airplanes, doctors smoked right in front of you, even Barney Rubble enjoyed a fag once and a while...
I think everyone is familiar with the fact that pretty much every celeb was a tobacco pusher at one time or another; the retro-blogs are littered with cigarette ads featuring the likes of Ronald Reagan, John Wayne and Lucille Ball. Not only that, but supposed medical doctors also peddled the cancer sticks in magazine ads.
So, picture yourself as a kid in a car with the windows rolled up and both parents are chain smoking - this was not at all uncommon in the 70's. Pregnant moms and juveniles often had no problem purchasing some coffin nails either. Ashtrays were everywhere: in the movie theater, in the church, at the library, in Sears, at the pool, in television commercials, etc. etc.
Don't misunderstand me, I'm not waxing nostalgic. Eradicating cigarettes has been a positive change, to be sure. It wasn't a pretty sight - possibly the worst thing was the cigarette butts EVERYWHERE. Time travel back to the 1970's, and take a look at any sidewalk in the country, and I guarantee you can't take two steps without seeing either a pop top or cigarette butt. Good riddance.