In my experience speed is one of several factors that condributes to a crash. Usually it is the driver that brings themselves unstuck. Yes cars have improved with safety over the years but also have plenty more power than what they use to. Increasing speed limits because cars have improved safety isn't the best idea. Cars don't improve a driver's aility to be able to avoid certain things. They certainly do help but the driver is the driver, car's don't drive themselves. Causing kaos on the road isn't the right way to go about it. All you are going to do is piss off other road users who more than likely have the same opinion on the subject as you. Also if speed doesn't kill go to a couple of fatal accidents where families have been involved. Speed in my experience has had some part to play. For example triple fatal in Wollongong about a year ago. Turned up to that stepped out of the car and didn't realise there was a head laying 2 lanes from the actual car. Found out 3 hours later that it was my wifes sisters boyfriend. I will give you one guess at what caused that accident... 200km/h in a 70km/h with a impact speed of 174km/h. Plenty more first hand examples so in short speed kills. It aint the only factor one of many.