I was only 2 when Ronnie Raygun took office, so there’s some stuff I just don’t get about the decade of my birth. Older folk, please lend a hand here. 
Youngsters, feel free to tag along & pester them too.
In no particular order:
Vans
Off-roading & dirt-bikes
CB radio
Semi trucks/drivers
Smileys
That’s it for today. I think I get the rest. 
Vans was about a mattress and quad sound in mobile platform. Also smoke containment habitats. Not good if the neighbors get a whiff.
Dirt bikes are all about the hanging your ass in a breeze and mostly about wrecking the knees. On a stump no less.
CB I’ll let someone else explain. That was a ‘80s thing I think. And goes hand in hand with the truckin’
Lotta vets took to long haul after the service back then I suspect.
My brain is somewhat old and addled and I cannot recall which came first the Wally World or the Smiley?
I was not born in the 70s, but that looks like a list focused on teenagers/young adults and is probably representative of California’s influence over that generation. Funny looking back and seeing how all of these things have made a come back at different points in time…i remember in Jr. High in the 90s how CBs came back for awhile. Had some friends who loved getting on and fucking w truckers and other people. Trucking never really went away but trucker hats made a big comeback!
One word: cocaine
Vans were awesome a mobile party, Vans were also very cheap at the beginning…dont come a knockin when the vans arockin
its a bad drug
Your list is quite reasonable considering the time, apart from maybe smilieys, that was more an 80s thang here.
What i’d like to hear an explanation for was the fashion crimes that era was famous for.
Guys in high heeled boots with flared trousers, huge belt buckles, shirts with collars so big they could snap your neck in a strong wind, massive mullet hair including guys with huge perms. Macho medallion men gyrating to gay anthems at the disco? WTF was going on?
You’d visit folks houses…mental psychedelic wallpaper, bright orange curtains, a lime green or brown vinyl sofa, brown and orange insane patterned carpets and then the Mrs of the house would appear in a brown corduroy dress with mustard yellow tights…
The thing is i thought it was all normal at the time (i was only a kid) but looking back…seems like we had finally found colour but had no idea what to do with it so we took far too much LSD, amphetamines etc and got very paranoid about the cold war and nuclear oblivion.
Dressed in silly clothes…
Nah i still don’t get the 70s and i was there 
CB radios were a truckers tool for staying awake and aware during long hauls. They were the closest thing to an internet after the telephone party line. A poor man’s mobile short-wave. There was an inscrutable coded vocabulary and culture that was likely ruined by a million 14 year olds who suddenly thought it would be cool to talk to passing truckers in the middle of the night. I wanted one but couldn’t afford the electronics.
This came out late in the game.
The CB radio “collapse” presaged a similar fate to the '93 “death” of the Internet (aka Usenet - Google “Eternal September”)
Vans: party room on wheels - many had beds, some had waterbeds
Off-roading & dirt-bikes - whats to understand? you go fast, you go places no car normally could or would go - you get stuck - you have to be towed out - wheee
CB radio - it was before cellphones or the internet - it was a way to meet people and have meaningless conversations or get updates on speed traps etc… Also hook-ups.
Semi trucks/drivers - it went along with the CB culture since truckers were the ones mainly using the CB radios, and ther was a sort of cowboy/rebel mythos around them at that time.
Smileys - a good happy feeling on a button or bumper sticker that was universal, and is still used to this day on forums like this 
I had platforms and elephant bells lol the bottom of those bells just awesome
Do not remember smileys in 70’s, do remember the peace sign 
I was out when you needed dirt bikes explained…but I now have the feeling I should explain what a snowflake is…
yeah i didnt even know what to say there i was riding in the 60’s
These are all things that never went out of style, IMO. None of them need any explanation!
I watched convoy during lockdown, hadn’t seen it in probably 30yrs, still found it entertaining
What killed CB here was the general public getting them, same with the club scene, festivals etc etc. The masses show up and it’s fucked.
Same things happening with ganja btw
a blast from the early 70’s in Michigan
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Yeah, Convoy. Good bad movie. Don’t forget Smokey & The Bandit the year before. I think everyone wanted a CB after that.
daughter and son were born during the 70’s, acid was pure magic and prog rock was out of this world, wife divorced me and took me back again, was quite a decade one way and another, i must be getting old daughter will be 50 next month.
This is really pretty perfect.