I looked up the stats going back a few decades - in the sixties, an average hundred kids died in traffic each year here in Norway. Now? Two or three. Yet we drive more and the population is significantly larger, too.
Drowning (the other biggie) is down by a similar factor.
Generic accidents? Also down by at least an order of magnitude.
We may sigh all we want that kids today are glued to their playstations while we were out building tree huts, conducting -ahem- applied pyrotechnics experiments and similar - but the fact of the matter is that kids today survive childhood. We didn't. :/
The main difference is being supervised by a reasonable adult or not and how streets near homes have changed.
Kids can only be left to free roam in a very safe environment - and even that is not entirely without risks. Alternatively only kids who are shown to be reasonable can do that - it takes parental sensitivity.