"Yet we see every day people taking their car ready to murder people without any single sense of responsibility."
Here in the Netherlands we didn't get to good bicycle infrastructure by trying to maximize the number of people in dangerous situations as a stepping stone, so maybe I'm missing something unique about the US.
Edit: asked an American friend and apparently in the US cyclists have to assert their presence since there aren't dedicated lanes, up to things like keeping a stick on your bike to hit cars that impinge on your rights. So that's certainly different. I still wouldn't put young children in that situation but it's certainly something quite different from here.
If there aren't enough riders, then the planners won't have the data to support painting some bike lanes to attract more riders and get people out of cars.
And then the car people will complain that the bike lane is taking up "their" road and planners will be forced to remove the bike lane or let it rot.
It's condescending to assume they can.
Yes, its dangerous, because other people make it dangerous. The unfortunate reality of living in America is that a lot of people do a lot of things that are not terribly hazardous to themselves but are quite hazardous to other people. As a parent, I have chosen to do what I can to mitigate the risks as best as I can, short of just staying home, or driving everywhere.
Honestly, this bicyclist was killed at a location where I would feel comfortable riding with my kids. Its fairly low traffic, has decent bike lanes, and the speed limit is low. The simple fact of the matter is that unless you build serious infrastructure, no bike thoroughfare is safe from sufficiently motivated/reckless/drunk drivers. Based on the accident details (especially the driver having minor injuries), this sounds like somebody driving waaaay too fast for the road. All of this to say, this isn't an argument for stopping biking, or biking without kids, but it is an argument for more aggressively enforcing traffic laws on these roads that are tempting to joy riders, and improving biking infrastructure so its harder for these accidents to occur.
We don't allow cars on BART/Caltrain tracks for example because it is dangerous to drivers.