I don't know about worldwide, but in Germany[1] the number of children injured or killed in traffic has been on a downward slope for about 40 years. That includes pedestrians. And despite the fact that number of cars has gone up up up[2].

Of course parents being more restrictive with their kids may well be one of the reasons why the number has gone down (there are many confounding factors).

[1] and, at first glance, most of Europe https://www.destatis.de/DE/Themen/Gesellschaft-Umwelt/Verkeh... (pages 53 onwards among others)

[2] +40% more cars, in absolute terms, than in 1990!! Crazy.