Cars aren't always to blame. It's just that it starts from the presumption that the car is at fault - which is the case in approx 90% of cases in the UK (although the UK doesn't have this strict-liability unfortunately)
No, cars aren't too blame, the car owner is only liable for damage, and why does that law exist? Because cars have mandatory liability insurance, bicycles and pedestrians do not. It's not about making drivers more responsible, although it helps most Dutch don't understand what liability means, it's too make sure there is always money to pay for damage, especially if the damage is severe.
Even in The Netherlands this law was needed to keep bikers safe.
And when introduced even the Dutch made fun of it: https://m.youtube.com/watch?v=ivY06w83fKU
Edit: if you want to look this up, the law is called: "Artikel 185 Wegenverkeerswet".
It's very broad and is not only to protect cyclists. I think this law is more about making drivers of motor vehicles more responsible.