Speaking as a plaintiff’s PI attorney and as a crappy driver, I prefer to think about something else.
I agree that there should be a presumption that drivers who are speeding are at fault in a collision. That’s why- gasp- they are.
As far as your second point, you live in a country where most states don’t require vehicles to be inspected for roadworthiness. Good luck holding a driver responsible for maintaining their vehicles according to a standard that doesn’t exist.