On a cul-de-sac, almost all the traffic is of people that live there. Hours can go by with absolutely no traffic.
Sidewalks are another issue. In car-oriented neighborhoods they are often non-existent, or an afterthought on only one side of the street. Sometimes they just randomly end, only to start again half a mile down the road. In older grid neighborhoods, sidewalks are wide, often separated from the street with a tree line, and are on both sides of the street. They are almost inviting kids to come play on them.
Also, there are sidewalks everywhere. My one big complaint is that the street lighting is pretty bad.
Well, I am glad you guys could stay safe, but I would rather send my daughter to play in some sort of kinder garden, park, or some facility made for that purpose rather then allowing her playing on the street.
Still, it is my personal feeling only, because I've had never lived in a suburbs like this.
There are parks and schools with playgrounds within a very short walk from my house. Like I mentioned in a different comment, my big complaint is the crappy street lighting. I don't mind my kids going out to play, but once the sun goes down it's pretty dark out and that makes me a little uncomfortable.
Just get your child a decent headlamp. Problem solved (this is how I solved the problem that it is quite funny to go inlineskating on summer nights, when it is already dark but still warm).