For hippies, it was also necessary for them to leave their parents' homes. In my own case, I left at 18, but knew many kids in high school who went homeless/hippy at 15 or 17. One was my best friend since 4th grade. Hippies were not all the same in their motivations either. But people could recognize them by their homelessness and raggedy appearance. Some among them were super religious, some among them walked barefoot, some wore dreadlocks - but the majority were just homeless kids who lived next to bus stations and train stations or in bushes near where rivers flowed out to the beaches. There was no housing they could afford, either. In fact, I'd say that it's easier now to find a minimum wage job than it was back then (my own home town had about 1/10 the restaurants and motels as it does now...you had to know someone to get a fast food job).
There was a serious affordable housing crisis in the 70's, as well. We lived in groups of 4-5 people (before cities passed ordinances disallowing it).
I think people forget that corporal punishment of children was permitted in the 70's, in nearly all states, that parents tried to exercise extremely strict control over every aspect of their kids' lives and teens did not get given cars in the same percentages as now. Hitchhiking at freeway on ramps was legal, so there were encampments up and down every freeway in California - but many of the kids came from inland states.
If Van Life isn't a movement, then neither were the hippies. In my professional opinion. Van Life became way. more popular when Alex Honnold revealed his van, his life style, etc. I have interviewed many young men who adore Alex and want to be just like him (and they're making good progress - I just managed to talk to an older climber about the whole situation, as he is a person who allows Van Lifers to stay on his property near Yosemite). There. are entire documentaries about this movement and the principles they think guide it.
Not everyone living in a van is a Van Lifer, but people who use #VanLife as their hash tag to monetize their experience are indeed an economic and cultural force, which is what a cultural movement is, by definition.
Here is a link to an academic article that discusses the main components of VanLife:
Van Life: A Creative Exploration of Contemporary Nomadism
it's a graphic one. 
