It's cars. It was always cars.
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The biggest change since then is two things.
One is that there’s way more to do inside now, mostly games and shows.
The second is that baseless kidnapping panics convinced society that children can never be unattended. The main vector was daytime TV and now true crime podcasts. The reality is that kidnapping is statistically extremely rare and more than 95% of all child sexual or other abuse is perpetrated by someone the child knows. Most kidnappings are also by someone the child knows.
Same in the 1970s/1980s. I grew up in a suburb-type neighborhood. Needed a car to go to work or to do any shopping or go basically anywhere. Rode a bus to school. The idea that car-centric development is a relatively new phenomenon is just wrong. It's been happening since the 1950s. We still played outside. We had TV but like 6 channels and nothing very interesting for a kid most of the time. Now we have ubiquitous computers and phones, and the sociopathic tech companies, which have really been just terrible for everyone except their investors.