This wasn't particularly dangerous. It was confined to a mile of a 4 lane road, straight, well lit, the businesses were set back a ways, no traffic. The kids knew if they caused trouble they'd be shut down. Frankly it was mostly just revving engines and showing off.

In those days you could buy a working 440 roadrunner that'd press your eyeballs back in their sockets for $400. I almost bought a 68 Chevy Super Sport with some massive engine in it for $600. Sometimes I wonder if it was a good thing I didn't buy it :-/ That car today would cost a bleedin fortune.

Those people who do free climbing, they're crazy, and have a short life expectancy. Not something I'd ever consider. But I'm not going to tell them they can't do it.

Your last sentence is a strawman argument.

After all your description sounds somehow safe, the problem would still be a ton accelaterated in public space which has nothing to do with free climbing

Things were different in those days. It was the peak of American car culture. Kids got their driver's license on their 16th birthday, not well into their 20's like today. Driving a cool car was a top priority, and teens all got jobs mostly to finance a car. Heck, I was doing burnouts in the driveway before I had a license :-)

Naturally, they'd race them. All over the place. By informally setting aside a safe boulevard at night for them to express those urges, the idea was things would be more safe, not less, and the cops could keep an eye on it to keep things from getting out of hand. After the cops were forced to shut it down, it went back to being distributed around the city in a much less safe manner.