It's cars. It was always cars.
Plenty of cars in the 90s and we played outside all day.
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.
I’m Belgium it was Dutroux. It changed everything and is a cross generational trauma that still has its effects.